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Sample records for position sensitive silicon

  1. Position sensitive silicon detectors inside the Tevatron collider

    International Nuclear Information System (INIS)

    Apollinari, G.; Bedeschi, F.; Bellettini, G.; Bosi, F.; Bosisio, L.; Cervelli, F.; Del Fabbro, R.; Dell'Orso, M.; Di Virgilio, A.; Focardi, E.; Giannetti, P.; Giorgi, M.; Menzione, A.; Ristori, L.; Scribano, A.; Sestini, P.; Stefanini, A.; Tonelli, G.; Zetti, F.; Bertolucci, S.; Cordelli, M.; Curatolo, M.; Dulach, B.; Esposito, B.; Giromini, P.; Miscetti, S.; Sansoni, A.

    1986-01-01

    Four position sensitive silicon detectors have been tested inside the Tevatron beam pipe at Fermilab. The system is the prototype of the small angle silicon spectrometer designed to study primarily p-anti p elastic and diffractive cross-sections at the Collider of Fermilab (CDF). Particles in the beam halo during p-anti p storage tests were used to study the performance of the detectors. Efficiency, linearity of response and spatial resolution are shown. Measurements performed at different distances from the beam axis have shown that the detectors could be operated at 8.5 mm from the beam with low rates and no disturbance to the circulating beams. This distance corresponds to about 11 times the standard half-width of the local beam envelope. The behaviour of the detectors with the radiation dose has also been investigated. (orig.)

  2. Two-dimensional position sensitive silicon photodiode as a charged particle detector

    International Nuclear Information System (INIS)

    Kovacevic, K.; Zadro, M.

    1999-01-01

    A two-dimensional position sensitive silicon photodiode has been tested for measurement of position and energy of charged particles. Position nonlinearity and resolution, as well as energy resolution and ballistic deficit were measured for 5.486 MeV α-particles. The results obtained for different pulse shaping time constants are presented

  3. Silicon position sensitive detectors for the Helios (NA 34) experiment

    Energy Technology Data Exchange (ETDEWEB)

    Engels, E Jr; Mani, S; Manns, T; Plants, D; Shepard, P F; Thompson, J A; Tosh, R; Chand, T; Shivpuri, R; Baker, W

    1987-01-15

    The design construction and testing of X-Y tracking modules for a silicon microstrip vertex detector for use in Fermilab experiment E706 is discussed. A successful adaptation of various technologies, essential for instrumenting this class of detectors at a university laboratory is described. Emphasis is placed on considerable cost reduction, design flexibiity and more rapid turnover with a view toward large detectors for the future.

  4. Position-sensitive silicon strip detector characterization using particle beams

    CERN Document Server

    Maenpaeae, Teppo

    2012-01-01

    Silicon strip detectors are fast, cost-effective and have an excellent spatial resolution.They are widely used in many high-energy physics experiments. Modern high energyphysics experiments impose harsh operation conditions on the detectors, e.g., of LHCexperiments. The high radiation doses cause the detectors to eventually fail as a resultof excessive radiation damage. This has led to a need to study radiation tolerance usingvarious techniques. At the same time, a need to operate sensors approaching the endtheir lifetimes has arisen.The goal of this work is to demonstrate that novel detectors can survive the environment that is foreseen for future high-energy physics experiments. To reach this goal,measurement apparatuses are built. The devices are then used to measure the propertiesof irradiated detectors. The measurement data are analyzed, and conclusions are drawn.Three measurement apparatuses built as a part of this work are described: two telescopes measuring the tracks of the beam of a particle acceler...

  5. On determining dead layer and detector thicknesses for a position-sensitive silicon detector

    Science.gov (United States)

    Manfredi, J.; Lee, Jenny; Lynch, W. G.; Niu, C. Y.; Tsang, M. B.; Anderson, C.; Barney, J.; Brown, K. W.; Chajecki, Z.; Chan, K. P.; Chen, G.; Estee, J.; Li, Z.; Pruitt, C.; Rogers, A. M.; Sanetullaev, A.; Setiawan, H.; Showalter, R.; Tsang, C. Y.; Winkelbauer, J. R.; Xiao, Z.; Xu, Z.

    2018-04-01

    In this work, two particular properties of the position-sensitive, thick silicon detectors (known as the "E" detectors) in the High Resolution Array (HiRA) are investigated: the thickness of the dead layer on the front of the detector, and the overall thickness of the detector itself. The dead layer thickness for each E detector in HiRA is extracted using a measurement of alpha particles emitted from a 212Pb pin source placed close to the detector surface. This procedure also allows for energy calibrations of the E detectors, which are otherwise inaccessible for alpha source calibration as each one is sandwiched between two other detectors. The E detector thickness is obtained from a combination of elastically scattered protons and an energy-loss calculation method. Results from these analyses agree with values provided by the manufacturer.

  6. A position sensitive silicon detector for AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy)

    CERN Multimedia

    Gligorova, A

    2014-01-01

    The AEḡIS experiment (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) is located at the Antiproton Decelerator (AD) at CERN and studies antimatter. The main goal of the AEḡIS experiment is to carry out the first measurement of the gravitational acceleration for antimatter in Earth’s gravitational field to a 1% relative precision. Such a measurement would test the Weak Equivalence Principle (WEP) of Einstein’s General Relativity. The gravitational acceleration for antihydrogen will be determined using a set of gravity measurement gratings (Moiré deflectometer) and a position sensitive detector. The vertical shift due to gravity of the falling antihydrogen atoms will be detected with a silicon strip detector, where the annihilation of antihydrogen will take place. This poster presents part of the development process of this detector.

  7. New technologies of silicon position-sensitive detectors for future tracker systems

    CERN Document Server

    Bassignana, Daniela; Lozano, M

    In view of the new generation of high luminosity colliders, HL-LHC and ILC, a farther investigation of silicon radiation detectors design and technology is demanded, in order to satisfy the stringent requirements of the experiments at such sophisticated machines. In this thesis, innovative technologies of silicon radiation detectors for future tracking systems are proposed. Three dierent devices have been studied and designed with the help of dierent tools for computer simulations. They have been manufactured in the IMB-CNM clean room facilities in Barcelona and characterized with proper experimental set-ups in order to test the detectors capabilities and the quality and suitability of the technologies used for their fabrication. The rst technology deals with the upgrade of dedicated sensors for laser alignment systems in future tracker detectors. The design and technology of common single-sided silicon microstrip detectors have been slightly modied in order to improve IR light transmittance of the devices. T...

  8. Front-end circuit for position sensitive silicon and vacuum tube photomultipliers with gain control and depth of interaction measurement

    International Nuclear Information System (INIS)

    Herrero, Vicente; Colom, Ricardo; Gadea, Rafael; Lerche, Christoph W.; Cerda, Joaquin; Sebastia, Angel; Benlloch, Jose M.

    2007-01-01

    Silicon Photomultipliers, though still under development for mass production, may be an alternative to traditional Vacuum Photomultipliers Tubes (VPMT). As a consequence, electronic front-ends initially designed for VPMT will need to be modified. In this simulation, an improved architecture is presented which is able to obtain impact position and depth of interaction of a gamma ray within a continuous scintillation crystal, using either kind of PM. A current sensitive preamplifier stage with individual gain adjustment interfaces the multi-anode PM outputs with a current division resistor network. The preamplifier stage allows to improve front-end processing delay and temporal resolution behavior as well as to increase impact position calculation resolution. Depth of interaction (DOI) is calculated from the width of the scintillation light distribution, which is related to the sum of voltages in resistor network input nodes. This operation is done by means of a high-speed current mode scheme

  9. Simulation and measurement of short infrared pulses on silicon position sensitive device

    International Nuclear Information System (INIS)

    Krapohl, D; Esebamen, O X; Nilsson, H E; Thungstroem, G

    2011-01-01

    Lateral position sensitive devices (PSD) are important for triangulation, alignment and surface measurements as well as for angle measurements. Large PSDs show a delay on rising and falling edges when irradiated with near infra-red light. This delay is also dependent on the spot position relative to the electrodes. It is however desirable in most applications to have a fast response. We investigated the responsiveness of a Sitek PSD in a mixed mode simulation of a two dimensional full sized detector. For simulation and measurement purposes focused light pulses with a wavelength of 850 nm, duration of 1μs and spot size of 280μm were used. The cause for the slopes of rise and fall time is due to time constants of the device capacitance as well as the photo-generation mechanism itself. To support the simulated results, we conducted measurements of rise and fall times on a physical device. Additionally, we quantified the homogeneity of the device by repositioning a spot of light from a pulsed ir-laser diode on the surface area.

  10. Silicon position-sensitive detectors for the Helios (NA 34) experiment

    Energy Technology Data Exchange (ETDEWEB)

    Engels, E Jr; Mani, S; Manns, T; Plants, D; Shepard, P F; Thompson, J A; Tosh, R; Chand, T; Shivpuri, R; Baker, W

    1987-01-15

    The design construction and testing of X-Y tracking modules for a silicon microstrip vertex detector for use in Fermilab experiment E706 is discussed. A successful adaptation of various technologies, essential for instrumenting this class of detectors at a university laboratory is described. Emphasis is placed on considerable cost reduction, design flexibiity and more rapid turnover with a view toward large detectors for the future.

  11. A readout system for position sensitive measurements of X-ray using silicon strip detectors

    CERN Document Server

    Dabrowski, W; Grybos, P; Idzik, M; Kudlaty, J

    2000-01-01

    In this paper we describe the development of a readout system for X-ray measurements using silicon strip detectors. The limitation concerning the inherent spatial resolution of silicon strip detectors has been evaluated by Monte Carlo simulation and the results are discussed. The developed readout system is based on the binary readout architecture and consists of two ASICs: RX32 front-end chip comprising 32 channels of preamplifiers, shapers and discriminators, and COUNT32 counter chip comprising 32 20-bit asynchronous counters and the readout logic. This work focuses on the design and performance of the front-end chip. The RX32 chip has been optimised for a low detector capacitance, in the range of 1-3 pF, and high counting rate applications. It can be used with DC coupled detectors allowing the leakage current up to a few nA per strip. For the prototype chip manufactured in a CMOS process all basic parameters have been evaluated by electronic measurements. The noise below 140 el rms has been achieved for a ...

  12. Simulation study of signal formation in position sensitive planar p-on-n silicon detectors after short range charge injection

    International Nuclear Information System (INIS)

    Peltola, T.; Eremin, V.; Verbitskaya, E.; Härkönen, J.

    2017-01-01

    Segmented silicon detectors (micropixel and microstrip) are the main type of detectors used in the inner trackers of Large Hadron Collider (LHC) experiments at CERN. Due to the high luminosity and eventual high fluence of energetic particles, detectors with fast response to fit the short shaping time of 20–25 ns and sufficient radiation hardness are required. Charge collection measurements carried out at the Ioffe Institute have shown a reversal of the pulse polarity in the detector response to short-range charge injection. Since the measured negative signal is about 30–60% of the peak positive signal, the effect strongly reduces the CCE even in non-irradiated detectors. For further investigation of the phenomenon the measurements have been reproduced by TCAD simulations. As for the measurements, the simulation study was applied for the p-on-n strip detectors similar in geometry to those developed for the ATLAS experiment and for the Ioffe Institute designed p-on-n strip detectors with each strip having a window in the metallization covering the p + implant, allowing the generation of electron-hole pairs under the strip implant. Red laser scans across the strips and the interstrip gap with varying laser diameters and Si-SiO 2 interface charge densities ( Q f ) were carried out. The results verify the experimentally observed negative response along the scan in the interstrip gap. When the laser spot is positioned on the strip p + implant the negative response vanishes and the collected charge at the active strip increases respectively. The simulation results offer a further insight and understanding of the influence of the oxide charge density in the signal formation. The main result of the study is that a threshold value of Q f , that enables negligible losses of collected charges, is defined. The observed effects and details of the detector response for different charge injection positions are discussed in the context of Ramo's theorem.

  13. Simulation study of signal formation in position sensitive planar p-on-n silicon detectors after short range charge injection

    Science.gov (United States)

    Peltola, T.; Eremin, V.; Verbitskaya, E.; Härkönen, J.

    2017-09-01

    Segmented silicon detectors (micropixel and microstrip) are the main type of detectors used in the inner trackers of Large Hadron Collider (LHC) experiments at CERN. Due to the high luminosity and eventual high fluence of energetic particles, detectors with fast response to fit the short shaping time of 20-25 ns and sufficient radiation hardness are required. Charge collection measurements carried out at the Ioffe Institute have shown a reversal of the pulse polarity in the detector response to short-range charge injection. Since the measured negative signal is about 30-60% of the peak positive signal, the effect strongly reduces the CCE even in non-irradiated detectors. For further investigation of the phenomenon the measurements have been reproduced by TCAD simulations. As for the measurements, the simulation study was applied for the p-on-n strip detectors similar in geometry to those developed for the ATLAS experiment and for the Ioffe Institute designed p-on-n strip detectors with each strip having a window in the metallization covering the p+ implant, allowing the generation of electron-hole pairs under the strip implant. Red laser scans across the strips and the interstrip gap with varying laser diameters and Si-SiO2 interface charge densities (Qf) were carried out. The results verify the experimentally observed negative response along the scan in the interstrip gap. When the laser spot is positioned on the strip p+ implant the negative response vanishes and the collected charge at the active strip increases respectively. The simulation results offer a further insight and understanding of the influence of the oxide charge density in the signal formation. The main result of the study is that a threshold value of Qf, that enables negligible losses of collected charges, is defined. The observed effects and details of the detector response for different charge injection positions are discussed in the context of Ramo's theorem.

  14. Calibration of the OPAL jet chamber with UV laser beams. Measurement of the beam position with position-sensitive silicon diodes (PSD)

    International Nuclear Information System (INIS)

    Koch, J.

    1990-03-01

    The OPAL jet chamber is calibrated with tracks produced by UV laser beams. Lateral effect diodes are used for monitoring the laser beam location in the detector. These position sensitive detectors locate the point of impact in two dimensions by the charge division method. Measurements on several diodes were carried out in order to calibrate these devices and to investigate to observed pin-cushion distortion. Using the telegraphers equation suitable expressions were obtained for describing the observed behaviour. It was shown that the magnetic field of OPAL as well as the UV laser wavelength and puls duration had no influence on the position information. (orig.)

  15. Silicon Drift Detectors development for position sensing

    International Nuclear Information System (INIS)

    Castoldi, A.; Guazzoni, C.; Hartmann, R.; Strueder, L.

    2007-01-01

    Novel Silicon Drift Detectors (SDDs) with multi-linear architecture specifically intended for 2D position sensing and imaging applications are presented and their achievable spatial, energy and time resolution are discussed. The capability of providing a fast timing of the interaction with nanosecond time resolution is a new available feature that allows operating the drift detector in continuous readout mode for coincidence imaging applications either with an external trigger or in self-timing. The application of SDDs with multi-linear architecture to Compton electrons' tracking within a single silicon layer and the achieved experimental results will be discussed

  16. Design of a charge sensitive preamplifier on high resistivity silicon

    International Nuclear Information System (INIS)

    Radeka, V.; Rehak, P.; Rescia, S.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Strueder, L.; Kemmer, J.

    1987-01-01

    A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the feedback loop. The output stage of the preamplifier can drive a load up to 20pF. The power dissipation of the preamplifier is 13mW. The amplifying elements are ''Single Sided Gate JFETs'' developed especially for this application. Preamplifiers connected to a low capacitance anode of a drift type detector should achieve a rise time of 20ns and have an equivalent noise charge (ENC), after a suitable shaping, of less than 50 electrons. This performance translates to a position resolution better than 3μm for silicon drift detectors. 6 refs., 9 figs

  17. Submicron position-sensitive detector

    Energy Technology Data Exchange (ETDEWEB)

    Pugatch, V M; Rosenfeld, A B; Litovchenko, P G; Barabash, L I; Nemets, O F; Pavlenko, Yu N; Vasiliev, Yu O [Ukrainian Academy of Sciences, Kiev (Ukraine). Inst. for Nuclear Research

    1992-08-01

    A method has been developed to measure precisely the coordinates of charged particles incident between adjacent strips of a strip detector. The position sensitivity of an inter-strip gap has been studied by means of a pulsed laser beam and irradiation by [alpha]-particles of a [sup 226]Ra-source. The capacitive division of charge generated by the incident particle depends on the position of its track. Its coordinates were determined by two-dimensional amplitude analysis of the charges collected by neighbouring strips. This method of coordinate determination applied to studies of spatial and energy distributions of electromagnetic as well as charged particle beams (including radioactive ion beams) of low intensity could provide the highest level of the precision limited by the track dimensions of charged particles, i.e. percents of a micrometer. (orig.).

  18. Position-sensitive superconductor detectors

    International Nuclear Information System (INIS)

    Kurakado, M.; Taniguchi, K.

    2016-01-01

    Superconducting tunnel junction (STJ) detectors and superconducting transition- edge sensors (TESs) are representative superconductor detectors having energy resolutions much higher than those of semiconductor detectors. STJ detectors are thin, thereby making it suitable for detecting low-energy X rays. The signals of STJ detectors are more than 100 times faster than those of TESs. By contrast, TESs are microcalorimeters that measure the radiation energy from the change in the temperature. Therefore, signals are slow and their time constants are typically several hundreds of μs. However, TESs possess excellent energy resolutions. For example, TESs have a resolution of 1.6 eV for 5.9-keV X rays. An array of STJs or TESs can be used as a pixel detector. Superconducting series-junction detectors (SSJDs) comprise multiple STJs and a single-crystal substrate that acts as a radiation absorber. SSJDs are also position sensitive, and their energy resolutions are higher than those of semiconductor detectors. In this paper, we give an overview of position-sensitive superconductor detectors.

  19. Porous silicon: X-rays sensitivity

    International Nuclear Information System (INIS)

    Gerstenmayer, J.L.; Vibert, Patrick; Mercier, Patrick; Rayer, Claude; Hyvernage, Michel; Herino, Roland; Bsiesy, Ahmad

    1994-01-01

    We demonstrate that high porosity anodically porous silicon is radioluminescent. Interests of this study are double. Firstly: is the construction of porous silicon X-rays detectors (imagers) possible? Secondly: is it necessary to protect silicon porous based optoelectronic systems from ionising radiations effects (spatial environment)? ((orig.))

  20. Ultrahigh temperature-sensitive silicon MZI with titania cladding

    Directory of Open Access Journals (Sweden)

    Jong-Moo eLee

    2015-05-01

    Full Text Available We present a possibility of intensifying temperature sensitivity of a silicon Mach-Zehnder interferometer (MZI by using a highly negative thermo-optic property of titania (TiO2. Temperature sensitivity of an asymmetric silicon MZI with a titania cladding is experimentally measured from +18pm/C to -340 pm/C depending on design parameters of MZI.

  1. Position-sensitive proportional counter

    International Nuclear Information System (INIS)

    Kopp, M.K.

    1980-01-01

    A position-sensitive proportional counter circuit uses a conventional (low-resistance, metal-wire anode) counter for spatial resolution of an ionizing event along the anode, which functions as an RC line. A pair of preamplifiers at the anode ends act as stabilized active-capacitance loads, each comprising a series-feedback, low-noise amplifier and a unity-gain, shunt-feedback amplifier whose output is connected through a feedback capacitor to the series-feedback amplifier input. The stabilized capacitance loading of the anode allows distributed RC-line position encoding and subsequent time difference decoding by sensing the difference in rise times of pulses at the anode ends where the difference is primarily in response to the distributed capacitance along the anode. This allows the use of lower resistance wire anodes for spatial radiation detection which simplifies the counter construction of handling of the anodes, and stabilizes the anode resistivity at high count rates (>10 6 counts/sec). (author)

  2. Photo-EMF Sensitivity of Porous Silicon Thin Layer–Crystalline Silicon Heterojunction to Ammonia Adsorption

    Directory of Open Access Journals (Sweden)

    Kae Dal Kwack

    2011-01-01

    Full Text Available A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light.

  3. Photo-EMF sensitivity of porous silicon thin layer-crystalline silicon heterojunction to ammonia adsorption.

    Science.gov (United States)

    Vashpanov, Yuriy; Jung, Jae Il; Kwack, Kae Dal

    2011-01-01

    A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light.

  4. Photo-EMF Sensitivity of Porous Silicon Thin Layer–Crystalline Silicon Heterojunction to Ammonia Adsorption

    Science.gov (United States)

    Vashpanov, Yuriy; Jung, Jae Il; Kwack, Kae Dal

    2011-01-01

    A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light. PMID:22319353

  5. Position-sensitive radiation detector

    International Nuclear Information System (INIS)

    Mathieson, E.; Smith, G.C.; Gilvin, P.J.

    1981-01-01

    Apparatus for sensing the position of radiation received has a plurality of receptors spaced in at least one line on which the position is to be determined, their outputs being associated to form at least two groups, the density of the receptors in each group varying along the line. The receptors may comprise cathode arrays of a multiwire proportional counter, with an anode array between, measuring along lines in directions x and y respectively. The density of the wires in the two groups, decreases in opposite directions. A circuit determines the ratio of the output of one group to the sum of the group outputs. In another embodiment a scintillator is viewed by a plurality of light guides, the ends of which adjacent to the scintillator form the receptors, the four groups of which each terminate on a photomultiplier. (author)

  6. Phase-sensitive optical processing in silicon waveguides

    DEFF Research Database (Denmark)

    Petermann, Klaus; Gajda, A.; Dziallas, Claudia

    2015-01-01

    Parametric optical signal processing is reviewed for silicon nano-rib-waveguides with a reverse-biased pin-junction. Phase-sensitive parametric amplification with a phase-sensitive extinction of more than 20 dB has been utilized for the regeneration of DPSK signals...

  7. Position-controlled epitaxial III-V nanowires on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Roest, Aarnoud L; Verheijen, Marcel A; Wunnicke, Olaf; Serafin, Stacey; Wondergem, Harry; Bakkers, Erik P A M [Philips Research Laboratories, Professor Holstlaan 4, 5656 AA Eindhoven (Netherlands); Kavli Institute of NanoScience, Delft University of Technology, PO Box 5046, 2600 GA Delft (Netherlands)

    2006-06-14

    We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction pole figures and cross-sectional transmission electron microscopy. We show preliminary results of two-terminal electrical measurements of III-V nanowires grown on silicon. E-beam lithography was used to predefine the position of the nanowires.

  8. Position-controlled epitaxial III-V nanowires on silicon

    International Nuclear Information System (INIS)

    Roest, Aarnoud L; Verheijen, Marcel A; Wunnicke, Olaf; Serafin, Stacey; Wondergem, Harry; Bakkers, Erik P A M

    2006-01-01

    We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction pole figures and cross-sectional transmission electron microscopy. We show preliminary results of two-terminal electrical measurements of III-V nanowires grown on silicon. E-beam lithography was used to predefine the position of the nanowires

  9. First investigation of a novel 2D position-sensitive

    CERN Document Server

    Bassignana, D; Jaramillo, R; Lozano, M; Munoz, F J; Pellegrini, G; Quirion, D; Vila, I

    2012-01-01

    This paper presents a first study of the performance of a novel 2D position-sensitive microstrip detector, where the resistive charge division method was implemented by replacing the metallic electrodes with resistive electrodes made of polycrystalline silicon. A characterization of two proof-of-concept prototypes with different values of the electrode resistivity was carried out using a pulsed Near Infra-Red laser. The experimental data were compared with the electrical simulation of the sensor equivalent circuit coupled to simple electronics readout circuits. The good agreement between experimental and simulation results establishes the soundness of resistive charge division method in silicon microstrip sensors and validates the developed simulation as a tool for the optimization of future sensor prototypes. Spatial resolution in the strip length direction depends on the ionizing event position. The average value obtained from the protype analysis is close to 1.2% of the strip length for a 6 MIP signal.

  10. Results from multipoint alignment monitoring using the new generation of amorphous silicon position detectors

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E. [CIEMAT, 28040 Madrid (Spain); Ferrando, A. [CIEMAT, 28040 Madrid (Spain)], E-mail: antonio.ferrando@ciemat.es; Josa, M.I.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C. [CIEMAT, 28040 Madrid (Spain); Calderon, A.; Gomez, G.; Gonzalez-Sanchez, F.J.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Ruiz-Arbol, P.; Sobron, M.; Vila, I.; Virto, A.L. [Instituto de Fisica de Cantabria (IFCA), CSIC-University of Cantabria Santander (Spain)] (and others)

    2008-08-11

    We present the measured performance of a new generation of large sensitive area (28x28 mm{sup 2}) semitransparent amorphous silicon position detector sensors. More than 100 units have been characterized. They show a very high performance. To illustrate a multipoint application, we present results from the monitoring of five sensors placed in a 5.5-m-long light path.

  11. Results from multipoint alignment monitoring using the new generation of amorphous silicon position detectors

    International Nuclear Information System (INIS)

    Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C.; Calderon, A.; Gomez, G.; Gonzalez-Sanchez, F.J.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Ruiz-Arbol, P.; Sobron, M.; Vila, I.; Virto, A.L.

    2008-01-01

    We present the measured performance of a new generation of large sensitive area (28x28 mm 2 ) semitransparent amorphous silicon position detector sensors. More than 100 units have been characterized. They show a very high performance. To illustrate a multipoint application, we present results from the monitoring of five sensors placed in a 5.5-m-long light path

  12. Large area two dimensional position sensitive detectors

    International Nuclear Information System (INIS)

    Sann, H.; Olmi, A.; Lynen, U.; Stelzer, H.; Gobbi, A.; Bock, R.

    1979-02-01

    After an introduction, a position-sensitive ionization chamber, a parallel-plate detector, and a multiwire position-sensitive chamber are described. Then the data acquisition and analysis methods are considered. Furthermore, the experimental methods for a multi-parameter experiment are described. Finally, the measurement of gamma-ray and neutron multiplicities and sequential fission is considered, and the results are presented. (HSI) [de

  13. Large-size high-performance transparent amorphous silicon sensors for laser beam position detection

    International Nuclear Information System (INIS)

    Calderon, A.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Sobron, M.; Vila, I.; Virto, A.L.; Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Luque, J.M.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C.; Koehler, C.; Lutz, B.; Schubert, M.B.; Werner, J.H.

    2006-01-01

    We present the measured performance of a new generation of semitransparent amorphous silicon position detectors. They have a large sensitive area (30x30mm 2 ) and show good properties such as a high response (about 20mA/W), an intrinsic position resolution better than 3μm, a spatial-point reconstruction precision better than 10μm, deflection angles smaller than 10μrad and a transmission power in the visible and NIR higher than 70%

  14. A position sensitive parallel plate avalanche counter

    International Nuclear Information System (INIS)

    Lombardi, M.; Tan Jilian; Potenza, R.; D'amico, V.

    1986-01-01

    A position sensitive parallel plate avalanche counter with a distributed constant delay-line-cathode (PSAC) is described. The strips formed on the printed board were served as the cathode and the delay line for readout of signals. The detector (PSAC) was operated in isobutane gas at the pressure range from 10 to 20 torr. The position resolution is better than 1 mm and the time resolution is about 350 ps, for 252 Cf fission-spectrum source

  15. Position sensitive x-ray detector

    International Nuclear Information System (INIS)

    Macchione, E.L.A.

    1990-01-01

    A multi ware position sensitive gas counter for X-ray detection was developed in our laboratory, making use of commercial delay-lines for position sensing. Six delay-line chips (50 ns delay each, 40 Mhz cut-off frequency) cover a total sensitive length of 150 mm leading to a delay-risetime ratio that allows for a high-resolution position detection. Tests using the 5,9 keV X-ray line from a 55 Fe source and integral linearity better than 0,1% and a maximal differential linearity of ±4,0% were obtained operating the detector with an Ar-C H 4 (90%-10%) gas mixture at 700 torr. Similar tests were performed, using the 8,04 keV line from a Cu x-ray tube. A total resolution of 330 μm, and the same integral and differential linearities were obtained. (author)

  16. Ultraviolet /UV/ sensitive phosphors for silicon imaging detectors

    Science.gov (United States)

    Viehmann, W.; Cowens, M. W.; Butner, C. L.

    1981-01-01

    The fluorescence properties of UV sensitive organic phosphors and the radiometric properties of phosphor coated silicon detectors in the VUV, UV, and visible wavelengths are described. With evaporated films of coronene and liumogen, effective quantum efficiencies of up to 20% have been achieved on silicon photodiodes in the vacuum UV. With thin films of methylmethacrylate (acrylic), which are doped with organic laser dyes and deposited from solution, detector quantum efficiencies of the order of 15% for wavelengths of 120-165 nm and of 40% for wavelengths above 190 nm have been obtained. The phosphor coatings also act as antireflection coatings and thereby enhance the response of coated devices throughout the visible and near IR.

  17. Triangulating the Position of Antimony Donors Implanted in Silicon

    Science.gov (United States)

    Bureau-Oxton, Chloe; Nielsen, Erik; Luhman, Dwight; Ten Eyck, Gregory; Pluym, Tammy; Wendt, Joel; Pioro-Ladrière, Michel; Lilly, Michael; Carroll, Malcolm

    2015-03-01

    A potential candidate for a quantum bit is a single Sb atom implanted in silicon. A single-electron-transistor (SET) situated close to an Sb donor can be used to measure the occupancy and spin of the electron on the donor while the lithographically patterned poly-silicon gates defining the SET can be used to control donor occupancy. In our samples two clusters of Sb donors have been implanted adjacent to opposite sides of the SET through a self-aligned process. In this talk, we will present experimental results that allow us to determine the approximate position of different donors by determining their relative capacitance to pairs of the SET's poly-silicon gates. We will present the results of capacitive-based modeling calculations that allow us to further locate the position of the donors. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  18. Signal processors for position-sensitive detectors

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Ken-ichi [Hosei Univ., Koganei, Tokyo (Japan). Coll. of Engineering

    1996-07-01

    Position-sensitive detectors (PSD) are widely used in following various fields: condensed matter studies, material engineering, medical radiology particle physics, astrophysics and industrial applications. X-ray diffraction analysis is one of the field where PSDs are the most important instruments. In this field, many types of PSAs are employed: position-sensitive proportional counters (PSPC), multi-wire proportional chambers (MWPC), imaging plates, image intensifiers combined CCD cameras and semiconductor array devices. Two readout systems used for PSDs, where one is a charge-division type with high stability and the other is an encoder with multiple delay, line readout circuits useful for fast counting, were reported in this paper. The multiple delay line encoding system can be applicable to high counting rate 1D and 2D gas proportional detectors. (G.K.)

  19. Two-dimensional position sensitive neutron detector

    Indian Academy of Sciences (India)

    The detector is a 3He + Kr filled multiwire proportional counter with charge division position readout and has a sensitive area of 345 mm × 345 mm, pixel size 5 mm × 5 mm, active depth 25 mm and is designed for efficiency of 70% for 4 Å neutrons. The detector is tested with 0.5 bar 3He + 1.5 bar krypton gas mixture in active ...

  20. Position-sensitive X-ray detectors

    International Nuclear Information System (INIS)

    Hendrix, J.

    1982-01-01

    In this review of the application of different types of position sensitive detectors to synchrotron radiation, discussion of the proportional counters based on the gas amplification principle forms a major part. Other topics reviewed are detector requirements, multiwire proportional chamber system, drift chamber type detectors, TV detectors, and recent developments, such as that based on a micro-channel plate as the amplifying element, and charge-coupled devices. (U.K.)

  1. Gas position sensitive x-ray detectors

    International Nuclear Information System (INIS)

    Barbosa, A.F.

    1994-12-01

    The construction of gas x-ray detectors used to count and localize x-ray photons in one and two dimensions is reported. The principles of operation of the detectors are described, as well as the electronic modules comprised in the data acquisition system. Results obtained with detectors built at CBPF are shown, illustrating the performance of the Linear Position Sensitive Detectors. (author). 6 refs, 14 figs

  2. Modification of inkjet printer for polymer sensitive layer preparation on silicon-based gas sensors

    Directory of Open Access Journals (Sweden)

    Tianjian Li

    2015-04-01

    Full Text Available Inkjet printing is a versatile, low cost deposition technology with the capabilities for the localized deposition of high precision, patterned deposition in a programmable way, and the parallel deposition of a variety of materials. This paper demonstrates a new method of modifying the consumer inkjet printer to prepare polymer-sensitive layers on silicon wafer for gas sensor applications. A special printing tray for the modified inkjet printer to support a 4-inch silicon wafer is designed. The positioning accuracy of the deposition system is tested, based on the newly modified printer. The experimental data show that the positioning errors in the horizontal direction are negligibly small, while the positioning errors in the vertical direction rise with the increase of the printing distance of the wafer. The method for making suitable ink to be deposited to form the polymer-sensitive layer is also discussed. In the testing, a solution of 0.1 wt% polyvinyl alcohol (PVA was used as ink to prepare a sensitive layer with certain dimensions at a specific location on the surface of the silicon wafer, and the results prove the feasibility of the methods presented in this article.

  3. POWRS: position-sensitive motif discovery.

    Directory of Open Access Journals (Sweden)

    Ian W Davis

    Full Text Available Transcription factors and the short, often degenerate DNA sequences they recognize are central regulators of gene expression, but their regulatory code is challenging to dissect experimentally. Thus, computational approaches have long been used to identify putative regulatory elements from the patterns in promoter sequences. Here we present a new algorithm "POWRS" (POsition-sensitive WoRd Set for identifying regulatory sequence motifs, specifically developed to address two common shortcomings of existing algorithms. First, POWRS uses the position-specific enrichment of regulatory elements near transcription start sites to significantly increase sensitivity, while providing new information about the preferred localization of those elements. Second, POWRS forgoes position weight matrices for a discrete motif representation that appears more resistant to over-generalization. We apply this algorithm to discover sequences related to constitutive, high-level gene expression in the model plant Arabidopsis thaliana, and then experimentally validate the importance of those elements by systematically mutating two endogenous promoters and measuring the effect on gene expression levels. This provides a foundation for future efforts to rationally engineer gene expression in plants, a problem of great importance in developing biotech crop varieties.BSD-licensed Python code at http://grassrootsbio.com/papers/powrs/.

  4. Position sensitive detector for X-ray photons

    International Nuclear Information System (INIS)

    Barbosa, A.F.

    1988-01-01

    This work reports the theoretical basis and the details of the construction process, characterization and application of gas X-ray position sensitive detectors. The unidimensional detector consists of a gas camera (argon and CH 4 ), a metallic anode, a cathode and a delay line. Details of the construction process are given in order to allow the reproduction of the detector. It has been characterized by measuring its spatial resolution, homogeneity and linerity. The built linear detector has been used to obtain diffraction diagrams from polycrystalline silicon, C 23 H 48 paraffin and glassy carbon. These diagrams have been compared with those obtained under equivalent conditions with a conventional proportional detector by the step scanning method. It has been shown that the detector provides diffraction diagrams of equivalent quality to those obtained by the step scanning method, in appreciably lower time intervals. (author) [pt

  5. Position sensitive detection of neutrons in high radiation background field.

    Science.gov (United States)

    Vavrik, D; Jakubek, J; Pospisil, S; Vacik, J

    2014-01-01

    We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high γ and e(-) radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 μm(2)) spectroscopic Timepix detector adapted for neutron detection utilizing very thin (10)B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10(-4).

  6. Position-sensitive X-ray detectors

    International Nuclear Information System (INIS)

    Hendrix, J.

    1982-01-01

    An overview is given of the different types of position-sensitive X-ray detectors used in kinetic studies of biological molecule state changes using X-ray diffraction with synchrotron radiation as a probe. The detector requirements and principles of operation of proportional counters are outlined. Multiwire proportional chamber systems and their readout techniques are described. Other detectors discussed include a drift chamber type detector, microchannel plates, charge-couple devices and, for high count rates, an integrating TV-detector. (U.K.)

  7. A porous silicon optical microcavity for sensitive bacteria detection

    International Nuclear Information System (INIS)

    Li Sha; Huang Jianfeng; Cai Lintao

    2011-01-01

    A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak (∼10 nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000 bacteria ml -1 at the level of relative standard deviation of 0.994 and detection limit of 20 bacteria ml -1 . The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing.

  8. A porous silicon optical microcavity for sensitive bacteria detection

    Science.gov (United States)

    Li, Sha; Huang, Jianfeng; Cai, Lintao

    2011-10-01

    A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak (~10 nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000 bacteria ml - 1 at the level of relative standard deviation of 0.994 and detection limit of 20 bacteria ml - 1. The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing.

  9. A porous silicon optical microcavity for sensitive bacteria detection

    Energy Technology Data Exchange (ETDEWEB)

    Li Sha; Huang Jianfeng; Cai Lintao, E-mail: lt.cai@siat.ac.cn [CAS Key Lab of Health Informatics, Shenzhen Key Laboratory of Cancer Nanotechnology, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China)

    2011-10-21

    A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak ({approx}10 nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000 bacteria ml{sup -1} at the level of relative standard deviation of 0.994 and detection limit of 20 bacteria ml{sup -1}. The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing.

  10. Large Size High Performance Transparent Amorphous Silicon Sensors for Laser Beam Position Detection and Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, A.; Martinez Rivero, C.; Matorras, F.; Rodrigo, T.; Sobron, M.; Vila, I.; Virto; Alberdi, J.; Arce, P.; Barcala, J. M.; Calvo, E.; Ferrando, A.; Josa, M. I.; Luque, J. M.; Molinero, A.; Navarrete, J.; Oller, J. C.; Kohler, C.; Lutz, B.; Schubert, M. B.

    2006-09-04

    We present the measured performance of a new generation of semitransparente amorphous silicon position detectors. They have a large sensitive area (30 x 30 mm2) and show good properties such as a high response (about 20 mA/W), an intinsic position resolution better than 3 m, a spatial point reconstruction precision better than 10 m, deflection angles smaller than 10 rad and a transmission power in the visible and NIR higher than 70%. In addition, multipoint alignment monitoring, using up to five sensors lined along a light path of about 5 meters, can be achieved with a resolution better than 20m. (Author)

  11. Large-size high-performance transparent amorphous silicon sensors for laser beam position detection

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, A. [Instituto de Fisica de Cantabria. CSIC-University of Cantabria, Santander (Spain); Martinez-Rivero, C. [Instituto de Fisica de Cantabria. CSIC-University of Cantabria, Santander (Spain); Matorras, F. [Instituto de Fisica de Cantabria. CSIC-University of Cantabria, Santander (Spain); Rodrigo, T. [Instituto de Fisica de Cantabria. CSIC-University of Cantabria, Santander (Spain); Sobron, M. [Instituto de Fisica de Cantabria. CSIC-University of Cantabria, Santander (Spain); Vila, I. [Instituto de Fisica de Cantabria. CSIC-University of Cantabria, Santander (Spain); Virto, A.L. [Instituto de Fisica de Cantabria. CSIC-University of Cantabria, Santander (Spain); Alberdi, J. [CIEMAT, Madrid (Spain); Arce, P. [CIEMAT, Madrid (Spain); Barcala, J.M. [CIEMAT, Madrid (Spain); Calvo, E. [CIEMAT, Madrid (Spain); Ferrando, A. [CIEMAT, Madrid (Spain)]. E-mail: antonio.ferrando@ciemat.es; Josa, M.I. [CIEMAT, Madrid (Spain); Luque, J.M. [CIEMAT, Madrid (Spain); Molinero, A. [CIEMAT, Madrid (Spain); Navarrete, J. [CIEMAT, Madrid (Spain); Oller, J.C. [CIEMAT, Madrid (Spain); Yuste, C. [CIEMAT, Madrid (Spain); Koehler, C. [Steinbeis-Transferzentrum fuer Angewandte Photovoltaik und Duennschichttechnik, Stuttgart (Germany); Lutz, B. [Steinbeis-Transferzentrum fuer Angewandte Photovoltaik und Duennschichttechnik, Stuttgart (Germany); Schubert, M.B. [Steinbeis-Transferzentrum fuer Angewandte Photovoltaik und Duennschichttechnik, Stuttgart (Germany); Werner, J.H. [Steinbeis-Transferzentrum fuer Angewandte Photovoltaik und Duennschichttechnik, Stuttgart (Germany)

    2006-09-15

    We present the measured performance of a new generation of semitransparent amorphous silicon position detectors. They have a large sensitive area (30x30mm{sup 2}) and show good properties such as a high response (about 20mA/W), an intrinsic position resolution better than 3{mu}m, a spatial-point reconstruction precision better than 10{mu}m, deflection angles smaller than 10{mu}rad and a transmission power in the visible and NIR higher than 70%.

  12. Large Size High Performance Transparent Amorphous Silicon Sensors for Laser Beam Position Detection and Monitoring

    International Nuclear Information System (INIS)

    Calderon, A.; Martinez Rivero, C.; Matorras, F.; Rodrigo, T.; Sobron, M.; Vila, I.; Virto; Alberdi, J.; Arce, P.; Barcala, J. M.; Calvo, E.; Ferrando, A.; Josa, M. I.; Luque, J. M.; Molinero, A.; Navarrete, J.; Oller, J. C.; Kohler, C.; Lutz, B.; Schubert, M. B.

    2006-01-01

    We present the measured performance of a new generation of semitransparente amorphous silicon position detectors. They have a large sensitive area (30 x 30 mm2) and show good properties such as a high response (about 20 mA/W), an intinsic position resolution better than 3 m, a spatial point reconstruction precision better than 10 m, deflection angles smaller than 10 rad and a transmission power in the visible and NIR higher than 70%. In addition, multipoint alignment monitoring, using up to five sensors lined along a light path of about 5 meters, can be achieved with a resolution better than 20m. (Author)

  13. Characterization of three high efficiency and blue sensitive silicon photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Otte, Adam Nepomuk, E-mail: otte@gatech.edu; Garcia, Distefano; Nguyen, Thanh; Purushotham, Dhruv

    2017-02-21

    We report about the optical and electrical characterization of three high efficiency and blue sensitive Silicon photomultipliers from FBK, Hamamatsu, and SensL. Key features of the tested devices when operated at 90% breakdown probability are peak photon detection efficiencies between 40% and 55%, temperature dependencies of gain and PDE that are less than 1%/°C, dark rates of ∼50 kHz/mm{sup 2} at room temperature, afterpulsing of about 2%, and direct optical crosstalk between 6% and 20%. The characteristics of all three devices impressively demonstrate how the Silicon-photomultiplier technology has improved over the past ten years. It is further demonstrated how the voltage and temperature characteristics of a number of quantities can be parameterized on the basis of physical models. The models provide a deeper understanding of the device characteristics over a wide bias and temperature range. They also serve as examples how producers could provide the characteristics of their SiPMs to users. A standardized parameterization of SiPMs would enable users to find the optimal SiPM for their application and the operating point of SiPMs without having to perform measurements thus significantly reducing design and development cycles.

  14. Position-sensitive transition-edge sensors

    International Nuclear Information System (INIS)

    Iyomoto, N.; Bandler, S.R.; Brekosky, R.P.; Chervenak, J.A.; Figueroa-Feliciano, E.; Finkbeiner, F.M.; Kelley, R.L.; Kilbourne, C.A.; Lindeman, M.A.; Murphy, K.; Porter, F.S.; Saab, T.; Sadleir, J.E.; Talley, D.J.

    2006-01-01

    We report the latest results from our development of Position-Sensitive Transition-edge sensors (PoSTs), which are one-dimensional imaging spectrometers. In PoSTs with segmented Au absorbers, we obtained 8eV energy resolution on K Kα lines, which is consistent to the baseline energy resolution and the design values, on all of the nine pixels, by choosing the best combination of the thermal conductance in absorbers and in links that connects the absorbers. The pulse decay time of 193μs is fast enough for our purpose. In a PoST with a continuous Bi/Cu absorber, by dividing the events into 63 effective pixels, we obtained energy resolutions of 16eV at the center 'pixel', which is comparable to the baseline energy resolution, and 33eV at the outer 'pixel'. The degradation of the energy resolution in the outer 'pixel' is due to position dependence, which we can cancel out by dividing the events into smaller 'pixels' when we have sufficient X-ray events

  15. Delay-Line Three-Dimensional Position Sensitive Radiation Detection

    Science.gov (United States)

    Jeong, Manhee

    High-resistivity silicon(Si) in large volumes and with good charge carrier transport properties has been produced and achieved success as a radiation detector material over the past few years due to its relatively low cost as well as the availability of well-established processing technologies. One application of that technology is in the fabrication of various position-sensing topologies from which the incident radiation's direction can be determined. We have succeeded in developing the modeling tools for investigating different position-sensing schemes and used those tools to examine both amplitude-based and time-based methods, an assessment that indicates that fine position-sensing can be achieved with simpler readout designs than are conventionally deployed. This realization can make ubiquitous and inexpensive deployment of special nuclear materials (SNM) detecting technology becomes more feasible because if one can deploy position-sensitive semiconductor detectors with only one or two contacts per side. For this purpose, we have described the delay-line radiation detector and its optimized fabrication. The semiconductor physics were simulated, the results from which guided the fabrication of the guard ring structure and the detector electrode, both of which included metal-field-plates. The measured improvement in the leakage current was confirmed with the fabricated devices, and the structures successfully suppressed soft-breakdown. We also demonstrated that fabricating an asymmetric strip-line structure successfully minimizing the pulse shaping and increases the distance through which one can propagate the information of the deposited charge distribution. With fabricated delay-line detectors we can acquire alpha spectra (Am-241) and gamma spectra (Ba-133, Co-57 and Cd-109). The delay-line detectors can therefore be used to extract the charge information from both ion and gamma-ray interactions. Furthermore, standard charge-sensitive circuits yield high SNR

  16. 2D position sensitive microstrip sensors with charge division along the strip Studies on the position measurement error

    CERN Document Server

    Bassignana, D; Fernandez, M; Jaramillo, R; Lozano, M; Munoz, F.J; Pellegrini, G; Quirion, D; Vila, I; Vitorero, F

    2013-01-01

    Position sensitivity in semiconductor detectors of ionizing radiation is usually achieved by the segmentation of the sensing diode junction in many small sensing elements read out separately as in the case of conventional microstrips and pixel detectors. Alternatively, position sensitivity can be obtained by splitting the ionization signal collected by one single electrode amongst more than one readout channel with the ratio of the collected charges depending on the position where the signal was primary generated. Following this later approach, we implemented the charge division method in a conventional microstrip detector to obtain position sensitivity along the strip. We manufactured a proofof-concept demonstrator where the conventional aluminum electrodes were replaced by slightly resistive electrodes made of strongly doped poly-crystalline silicon and being readout at both strip ends. Here, we partially summarize the laser characterization of this first proof-of-concept demonstrator with special emphasis ...

  17. XPS study of palladium sensitized nano porous silicon thin film

    Indian Academy of Sciences (India)

    Keywords. Porous silicon; passivation; palladium; oxidation; XPS. Abstract. Nano porous silicon (PS) was formed on -type monocrystalline silicon of 2–5 cm resistivity and (100) orientation by electrochemical anodization method using HF and ethanol as the electrolytes. High density of surface states, arising due to its ...

  18. Performance of high-resolution position-sensitive detectors developed for storage-ring decay experiments

    International Nuclear Information System (INIS)

    Yamaguchi, T.; Suzaki, F.; Izumikawa, T.; Miyazawa, S.; Morimoto, K.; Suzuki, T.; Tokanai, F.; Furuki, H.; Ichihashi, N.; Ichikawa, C.; Kitagawa, A.; Kuboki, T.; Momota, S.; Nagae, D.; Nagashima, M.; Nakamura, Y.; Nishikiori, R.; Niwa, T.; Ohtsubo, T.; Ozawa, A.

    2013-01-01

    Highlights: • Position-sensitive detectors were developed for storage-ring decay spectroscopy. • Fiber scintillation and silicon strip detectors were tested with heavy ion beams. • A new fiber scintillation detector showed an excellent position resolution. • Position and energy detection by silicon strip detectors enable full identification. -- Abstract: As next generation spectroscopic tools, heavy-ion cooler storage rings will be a unique application of highly charged RI beam experiments. Decay spectroscopy of highly charged rare isotopes provides us important information relevant to the stellar conditions, such as for the s- and r-process nucleosynthesis. In-ring decay products of highly charged RI will be momentum-analyzed and reach a position-sensitive detector set-up located outside of the storage orbit. To realize such in-ring decay experiments, we have developed and tested two types of high-resolution position-sensitive detectors: silicon strips and scintillating fibers. The beam test experiments resulted in excellent position resolutions for both detectors, which will be available for future storage-ring experiments

  19. POSSuMUS: a position sensitive scintillating muon SiPM detector

    CERN Document Server

    Ruschke, Alexander

    The development of a modular designed large scale scintillation detector with a two-dimensional position sensitivity is presented in this thesis. This novel POsition Sensitive Scintillating MUon SiPM Detector is named POSSuMUS. The POSSuMUS detector is capable to determine the particle’s position in two space dimensions with a fast trigger capability. Each module is constructed from two trapezoidal shaped plastic scintillators to form one rectangular shaped detector module. Both trapezoids are optically insulated against each other. In both trapezoids the scintillation light is collected by plastic fibers and guided towards silicon photomultipliers (SiPMs). SiPMs are light sensors which are capable to detect even smallest amounts of light. By combining several detector modules, position sensitive areas from 100 cm2 to few m2 are achievable with few readout channels. Therefore, POSSuMUS provides a cost effective detector concept. The position sensitivity along the trapezoidal geometry of one detector module ...

  20. Silicon nanowire structures as high-sensitive pH-sensors

    International Nuclear Information System (INIS)

    Belostotskaya, S O; Chuyko, O V; Kuznetsov, A E; Kuznetsov, E V; Rybachek, E N

    2012-01-01

    Sensitive elements for pH-sensors created on silicon nanostructures were researched. Silicon nanostructures have been used as ion-sensitive field effect transistor (ISFET) for the measurement of solution pH. Silicon nanostructures have been fabricated by 'top-down' approach and have been studied as pH sensitive elements. Nanowires have the higher sensitivity. It was shown, that sensitive element, which is made of 'one-dimensional' silicon nanostructure have bigger pH-sensitivity as compared with 'two-dimensional' structure. Integrated element formed from two p- and n-type nanowire ISFET ('inverter') can be used as high sensitivity sensor for local relative change [H+] concentration in very small volume.

  1. Low-resistivity photon-transparent window attached to photo-sensitive silicon detector

    International Nuclear Information System (INIS)

    Holland, S.E.

    2000-01-01

    The invention comprises a combination of a low resistivity, or electrically conducting, silicon layer that is transparent to long or short wavelength photons and is attached to the backside of a photon-sensitive layer of silicon, such as a silicon wafer or chip. The window is applied to photon sensitive silicon devices such as photodiodes, charge-coupled devices, active pixel sensors, low-energy x-ray sensors and other radiation detectors. The silicon window is applied to the back side of a photosensitive silicon wafer or chip so that photons can illuminate the device from the backside without interference from the circuit printed on the frontside. A voltage sufficient to fully deplete the high-resistivity photosensitive silicon volume of charge carriers is applied between the low-resistivity back window and the front, patterned, side of the device. This allows photon-induced charge created at the backside to reach the front side of the device and to be processed by any circuitry attached to the front side. Using the inventive combination, the photon sensitive silicon layer does not need to be thinned beyond standard fabrication methods in order to achieve full charge-depletion in the silicon volume. In one embodiment, the inventive backside window is applied to high resistivity silicon to allow backside illumination while maintaining charge isolation in CCD pixels

  2. Position-controlled epitaxial III-V nanowires on silicon

    NARCIS (Netherlands)

    Roest, A.L.; Verheijen, M.A.; Wunnicke, O.; Serafin, S.N.; Wondergem, H.J.; Bakkers, E.P.A.M.

    2006-01-01

    We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction

  3. High-Sensitivity Temperature-Independent Silicon Photonic Microfluidic Biosensors

    Science.gov (United States)

    Kim, Kangbaek

    Optical biosensors that can precisely quantify the presence of specific molecular species in real time without the need for labeling have seen increased use in the drug discovery industry and molecular biology in general. Of the many possible optical biosensors, the TM mode Si biosensor is shown to be very attractive in the sensing application because of large field amplitude on the surface and cost effective CMOS VLSI fabrication. Noise is the most fundamental factor that limits the performance of sensors in development of high-sensitivity biosensors, and noise reduction techniques require precise studies and analysis. One such example stems from thermal fluctuations. Generally SOI biosensors are vulnerable to ambient temperature fluctuations because of large thermo-optic coefficient of silicon (˜2x10 -4 RIU/K), typically requiring another reference ring and readout sequence to compensate temperature induced noise. To address this problem, we designed sensors with a novel TM-mode shallow-ridge waveguide that provides both large surface amplitude for bulk and surface sensing. With proper design, this also provides large optical confinement in the aqueous cladding that renders the device athermal using the negative thermo-optic coefficient of water (~ --1x10-4RIU/K), demonstrating cancellation of thermo-optic effects for aqueous solution operation near 300K. Additional limitations resulting from mechanical actuator fluctuations, stability of tunable lasers, and large 1/f noise of lasers and sensor electronics can limit biosensor performance. Here we also present a simple harmonic feedback readout technique that obviates the need for spectrometers and tunable lasers. This feedback technique reduces the impact of 1/f noise to enable high-sensitivity, and a DSP lock-in with 256 kHz sampling rate can provide down to micros time scale monitoring for fast transitions in biomolecular concentration with potential for small volume and low cost. In this dissertation, a novel

  4. 32 CFR 154.13 - Sensitive positions.

    Science.gov (United States)

    2010-07-01

    ...) Critical-sensitive. (A) Access to Top Secret information. (B) Development or approval of plans, policies... report required in subpart K. (e) Billet control system for Top Secret. (1) To standardize and control the issuance of Top Secret clearances within the Department of Defense, a specific designated billet...

  5. On selecting a sensitive region thickness of a silicon semiconductor detector for operation under counting conditions

    International Nuclear Information System (INIS)

    Pronkin, N.S.; Khakhalin, V.V.

    1972-01-01

    The paper discusses the selection of a thickness of a sensitive area of a silicon semiconductor detector, used in the count regime based on the signal to noise ratio and β-radiation registration efficiency. (author)

  6. Study of position resolution and electron-hadron separation of electromagnetic calorimeter with a silicon structure

    International Nuclear Information System (INIS)

    Gorodnichev, V.B.; Kachanov, V.A.; Khodyrev, V.Yu.; Kurchaninov, L.L.; Rykali, V.V.; Solovianov, V.L.; Ukhalov, M.N.

    1993-01-01

    The maximum shower silicon strip detectors embedded in a module of sandwich-type electromagnetic calorimeter have been tested. The position resolution at different depths of the silicon structure has been measured. The results on electron-hadron separation obtained as a byproduct in this study are presented, and possibility of their improvement is discussed. 8 refs., 10 figs., 1 tab

  7. Use of position sensitive detectors in medicine

    International Nuclear Information System (INIS)

    Soussaline, F.

    1982-10-01

    Medical imagery is a field where developments in physics, engineering and instrumentation can be applied directly to human diagnosis and treatment. The need to detect ever-smaller anomalies and to measure increasingly slight variations in metabolic parameters has led to a high degree of complexity in radiographic, echographic and nuclear medicine instrumentation. The wide-spread use of digital circuits and more generally the development of data processing systems and mathematical algorithms has allowed the introduction of new techniques such as emission and transmission tomography, digitalised radiography, synchronised gamma cardiology and nuclear magnetic resonance. For reasons of brevity this article is confined to the presentation of some concepts and results in the field of computer-assisted tomography and a discussion on the main parameters of imagery systems using position detectors

  8. Experimental Demonstration of Phase Sensitive Parametric Processes in a Nano-Engineered Silicon Waveguide

    DEFF Research Database (Denmark)

    Kang, Ning; Fadil, Ahmed; Pu, Minhao

    2013-01-01

    We demonstrate experimentally phase-sensitive processes in nano-engineered silicon waveguides for the first time. Furthermore, we highlight paths towards the optimization of the phase-sensitive extinction ratio under the impact of two-photon and free-carrier absorption.......We demonstrate experimentally phase-sensitive processes in nano-engineered silicon waveguides for the first time. Furthermore, we highlight paths towards the optimization of the phase-sensitive extinction ratio under the impact of two-photon and free-carrier absorption....

  9. Position calibration of silicon strip detector using quasi-elastic scattering of 16O+197Au

    International Nuclear Information System (INIS)

    Yan Wenqi; Hu Hailong; Zhang Gaolong

    2013-01-01

    Background: Elastic scattering is induced by weakly unstable nuclei. Generally, a good angular resolution for angular distribution of elastic scattering is needed. The silicon strip detector is often used for this kind of experiment. Purpose: In order to use silicon strip detector to study the elastic scattering of weakly unbound nuclei, it is important to get the information of its position calibration. It is well known that the elastic scattering of stable nuclei has a good angular distribution and many experimental data have been obtained. Methods: So the scattering of stable nuclei can be used to calibrate the position information of silicon strip detector. In this experiment, the positions of silicon strip detectors are calibrated using 101 MeV and 59 MeV 16 O scattering on the 197 Au target. Results: The quasi-elastic peaks can be observed in the silicon strip detectors and the counts of quasi-elastic 16 O can be obtained. The solid angles of the silicon strip detectors are calibrated by using alpha source which has three alpha energy values. The angular distribution of quasi-elastic scattering of 16 O+ 197 Au is obtained at these two energy values. Conclusions: The experimental data of angular distribution are reasonable and fit for the principle of angular distribution of elastic scattering. It is concluded that in the experiment these silicon strip detectors can accurately give the position information and can be used for the elastic scattering experiment. (authors)

  10. First Investigation on a novel 2D position sensitive semiconductor detector concept

    CERN Document Server

    Bassignana, D; Jaramillo, R; Lozano, M; Munoz, F.J; Pellegrini, G; Quirion, D; Vila, I

    2012-01-01

    This paper presents a first study of the performance of a novel 2D position-sensitive microstrip detector, where the resistive charge division method was implemented by replacing the metallic electrodes with resistive electrodes made of polycrystalline silicon. A characterization of two proof-of-concept prototypes with different values of the electrode resistivity was carried out using a pulsed Near Infra-Red laser. The experimental data were compared with the electrical simulation of the sensor equivalent circuit coupled to simple electronics readout circuits. The good agreement between experimental and simulation results establishes the soundness of resistive charge division method in silicon microstrip sensors and validates the developed simulation as a tool for the optimization of future sensor prototypes. Spatial resolution in the strip length direction depends on the ionizing event position. The average value obtained from the protype analysis is close to 1.2% of the strip length for a 6 MIP signal.

  11. Experimental and numerical studies on the sensitivity of carbon fibre/silicone rubber composite sensors

    International Nuclear Information System (INIS)

    Yang, Lili; Ge, Yong; Zhu, Qinghua; Zhang, Ce; Wang, Zongpeng; Liu, Penghuan

    2012-01-01

    Flexible conductive composite sensors are of great importance for applications in structural monitoring due to their low cost, high durability and excellent compatibility. In this work, carbon fibre/silicone rubber composites were prepared and their sensitivity near the percolation threshold was investigated experimentally and theoretically. Results show that carbon fibre/silicone rubber composites have great mechanical and sensitivity even under high strain conditions. Two models based on the tunnelling effect and general effective medium theory were found to understand the sensitivity of composites with lower and higher fractions of carbon fibre. Moreover, the reversibility of the sensing performance is improved with the increase of carbon fibre addition. (paper)

  12. Illumination-invariant face recognition with a contrast sensitive silicon retina

    Energy Technology Data Exchange (ETDEWEB)

    Buhmann, J.M. [Rheinische Friedrich-Wilhelms-Univ., Bonn (Germany). Inst. fuer Informatik II; Lades, M. [Bochum Univ. (Germany). Inst. fuer Neuroinformatik; Eeckman, F. [Lawrence Livermore National Lab., CA (United States)

    1993-11-29

    Changes in lighting conditions strongly effect the performance and reliability of computer vision systems. We report face recognition results under drastically changing lighting conditions for a computer vision system which concurrently uses a contrast sensitive silicon retina and a conventional, gain controlled CCD camera. For both input devices the face recognition system employs an elastic matching algorithm with wavelet based features to classify unknown faces. To assess the effect of analog on-chip preprocessing by the silicon retina the CCD images have been digitally preprocessed with a bandpass filter to adjust the power spectrum. The silicon retina with its ability to adjust sensitivity increases the recognition rate up to 50 percent. These comparative experiments demonstrate that preprocessing with an analog VLSI silicon retina generates image data enriched with object-constant features.

  13. Sensitivity of energy-packed compounds based on superfine and nanoporous silicon to pulsed electrical treatments

    Energy Technology Data Exchange (ETDEWEB)

    Zegrya, G. G. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Savenkov, G. G. [Saint-Petersburg State Engineering Institute (Technical University) (Russian Federation); Morozov, V. A. [Saint-Petersburg State University (Russian Federation); Zegrya, A. G.; Ulin, N. V., E-mail: Ulin@mail.ioffe.ru; Ulin, V. P. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Lukin, A. A. [Saint-Petersburg State Engineering Institute (Technical University) (Russian Federation); Bragin, V. A.; Oskin, I. A. [AO Scientific Production Association Poisk (Russian Federation); Mikhailov, Yu. M. [Russian Academy of Sciences, Institute of Problems of Chemical Physics (Russian Federation)

    2017-04-15

    The sensitivity of an energy-packed compound based on nanoporous silicon and calcium perchlorate to a high-current electron beam is studied. The initiation of explosive transformations in a mixture of potassium picrate with a highly dispersed powder of boron-doped silicon by means of a high-voltage discharge is examined. It is shown that explosive transformation modes (combustion and explosion) appear in the energy-packed compound under study upon its treatment with an electron beam. A relationship is established between the explosive transformation modes and the density of the energy-packed compound and between the breakdown (initiation) voltage and the mass fraction of the silicon powder.

  14. Engineered porous silicon counter electrodes for high efficiency dye-sensitized solar cells.

    Science.gov (United States)

    Erwin, William R; Oakes, Landon; Chatterjee, Shahana; Zarick, Holly F; Pint, Cary L; Bardhan, Rizia

    2014-06-25

    In this work, we demonstrate for the first time, the use of porous silicon (P-Si) as counter electrodes in dye-sensitized solar cells (DSSCs) with efficiencies (5.38%) comparable to that achieved with platinum counter electrodes (5.80%). To activate the P-Si for triiodide reduction, few layer carbon passivation is utilized to enable electrochemical stability of the silicon surface. Our results suggest porous silicon as a promising sustainable and manufacturable alternative to rare metals for electrochemical solar cells, following appropriate surface modification.

  15. Position sensitive detector used to detect beam profile

    International Nuclear Information System (INIS)

    Zhao Xiaoyan; Zhao Zhizheng; Zu Kailing; Zheng Jianhua; Wang Yifang

    2003-01-01

    In order to study the detecting system of the residual-gas beam profile, we introduce the principle and construction of the Position Sensitive Detector (PSD). The performance of PSD is tested. Position resolution, position linearity, detection efficiency and background are obtained

  16. 14C autoradiography with an energy-sensitive silicon pixel detector.

    Science.gov (United States)

    Esposito, M; Mettivier, G; Russo, P

    2011-04-07

    The first performance tests are presented of a carbon-14 ((14)C) beta-particle digital autoradiography system with an energy-sensitive hybrid silicon pixel detector based on the Timepix readout circuit. Timepix was developed by the Medipix2 Collaboration and it is similar to the photon-counting Medipix2 circuit, except for an added time-based synchronization logic which allows derivation of energy information from the time-over-threshold signal. This feature permits direct energy measurements in each pixel of the detector array. Timepix is bump-bonded to a 300 µm thick silicon detector with 256 × 256 pixels of 55 µm pitch. Since an energetic beta-particle could release its kinetic energy in more than one detector pixel as it slows down in the semiconductor detector, an off-line image analysis procedure was adopted in which the single-particle cluster of hit pixels is recognized; its total energy is calculated and the position of interaction on the detector surface is attributed to the centre of the charge cluster. Measurements reported are detector sensitivity, (4.11 ± 0.03) × 10(-3) cps mm(-2) kBq(-1) g, background level, (3.59 ± 0.01) × 10(-5) cps mm(-2), and minimum detectable activity, 0.0077 Bq. The spatial resolution is 76.9 µm full-width at half-maximum. These figures are compared with several digital imaging detectors for (14)C beta-particle digital autoradiography.

  17. Digital position sensitive discrimination for 2-dimensional scintillation detectors

    International Nuclear Information System (INIS)

    Engels, R.; Reinartz, R.; Reinhart, P.

    1996-01-01

    The energy sensitivity of a two-dimensional scintillation gamma detector based on position sensitive photomultipliers has been minimized by a digital differential discrimination unit. Since the photomultiplier gain is position-dependent by 50%, a discrimination unit has been developed where digital upper and lower discrimination levels are set due to the position-dependent photomultiplier gain obtained from calibration measurements. Depending on the spatial resolution there can be up to 65.536 position-sensitive discriminator levels defining energy windows. By this method, narrow discriminator windows can be used for reducing the low and high energy quanta without effecting the sensitivity of the detector. The new discrimination method, its performance and test measurements with gamma rays will be described. Furthermore experimental results are presented

  18. Vertically etched silicon nano-rods as a sensitive electron detector

    International Nuclear Information System (INIS)

    Hajmirzaheydarali, M; Akbari, M; Soleimani-Amiri, S; Sadeghipari, M; Shahsafi, A; Akhavan Farahani, A; Mohajerzadeh, S

    2015-01-01

    We have used vertically etched silicon nano-rods to realize electron detectors suitable for scanning electron microscopes. The results of deep etching of silicon nano-structures are presented to achieve highly ordered arrays of nano-rods. The response of the electron detector to energy of the primary electron beam and the effects of various sizes and materials has been investigated, indicating its high sensitivity to secondary and back-scattered electrons. The miniaturized structure of this electron detector allows it to be placed in the vicinity of the specimen to improve the resolution and contrast. This detector collects electrons and converts the electron current to voltage directly by means of n-doped silicon nano-rods on a p-type silicon substrate. Silicon nano-rods enhance the surface-to-volume ratio of the detector as well as improving the yield of electron detection. The use of nano-structures and silicon nanowires as an electron detector has led to higher sensitivities than with micro-structures. (paper)

  19. Two-dimensional position sensitive Si(Li) detector

    International Nuclear Information System (INIS)

    Walton, J.T.; Hubbard, G.S.; Haller, E.E.; Sommer, H.A.

    1978-11-01

    Circular, large-area two-dimensional Si(Li) position sensitive detectors have been fabricated. The detectors employ a thin lithium-diffused n + resisitive layer for one contact and a boron implanted p + resistive layer for the second contact. A position resolution of the order of 100 μm is indicated

  20. A TWO-DIMENSIONAL POSITION SENSITIVE SI(LI) DETECTOR

    Energy Technology Data Exchange (ETDEWEB)

    Walton, Jack T.; Hubbard, G. Scott; Haller, Eugene E.; Sommer, Heinrich A.

    1978-11-01

    Circular, large-area two-dimensional Si(Li) position sensitive detectors have been fabricated. The detectors employ a thin lithium-diffused n{sup +} resistive layer for one contact and a boron implanted p{sup +} resistive layer for the second contact. A position resolution of the order of 100 {micro}m is indicated.

  1. Vantage sensitivity: individual differences in response to positive experiences.

    Science.gov (United States)

    Pluess, Michael; Belsky, Jay

    2013-07-01

    The notion that some people are more vulnerable to adversity as a function of inherent risk characteristics is widely embraced in most fields of psychology. This is reflected in the popularity of the diathesis-stress framework, which has received a vast amount of empirical support over the years. Much less effort has been directed toward the investigation of endogenous factors associated with variability in response to positive influences. One reason for the failure to investigate individual differences in response to positive experiences as a function of endogenous factors may be the absence of adequate theoretical frameworks. According to the differential-susceptibility hypothesis, individuals generally vary in their developmental plasticity regardless of whether they are exposed to negative or positive influences--a notion derived from evolutionary reasoning. On the basis of this now well-supported proposition, we advance herein the new concept of vantage sensitivity, reflecting variation in response to exclusively positive experiences as a function of individual endogenous characteristics. After distinguishing vantage sensitivity from theoretically related concepts of differential-susceptibility and resilience, we review some recent empirical evidence for vantage sensitivity featuring behavioral, physiological, and genetic factors as moderators of a wide range of positive experiences ranging from family environment and psychotherapy to educational intervention. Thereafter, we discuss genetic and environmental factors contributing to individual differences in vantage sensitivity, potential mechanisms underlying vantage sensitivity, and practical implications. 2013 APA, all rights reserved

  2. Recyclability of mixed office waste papers containing pressure sensitive adhesives and silicone release liners

    Science.gov (United States)

    Julie Hess; Roberta Sena-Gomes; Lisa Davie; Marguerite Sykes

    2001-01-01

    Increased use of pressure sensitive adhesives for labels and stamps has introduced another contaminant into the office paper stream: silicone- coated release liners. This study examines methods and conditions for removal of contaminants, including these liners, from a typical batch of discarded office papers. Removal of contaminants contained in the furnish were...

  3. Position Reconstruction and Charge Distribution in LHCb VELO Silicon Sensors

    CERN Document Server

    Versloot, TW; Akiba, K; Artuso, M; Van Beuzekom, M; Borel, J; Bowcock, TJV; Buytaert, J; Collins, P; Dumps, R; Dwyer, L; Eckstein, D; Eklund, L; Ferro-Luzzi, M; Frei, R; Gersabek M; Haefeli, G; Hennessy, K; Huse, T; Jans, E; John, M; Ketel, TJ; Keune, A; Lastoviicka, T; Mountain, R; Neufeld, N; Parkes, C; Stone, S; Szumlak, T; Tobin, M; Van Lysebetten, A; Viret, S; De Vries, H; Wang, J

    2007-01-01

    In 2006, a partially equipped LHCb VELO detector half was characterised in a test beam experiment (Alignment Challenge and Detector Commissioning, ACDC3). The position reconstruction and resolution for 2-strip R-sensor clusters was studied as a function of strip pitch and track inclination on the sensor surface. The Charge Density Distribution (CDD) is derived from the weighted charge distribution. It becomes asymmetric for tracks non-perpendicular to the strip surface. It is shown that the asymmetric broadening of the CDD around the track intercept position results in a linear eta-function at higher angles (>6 degrees). The sensor spatial resolution is determined both using a linear weighted mean of strip charges, as well as a third-order polynomial approximation via a eta-correction. The experimental results are in agreement with previous simulations. Future studies are underway to determine the angle and pitch dependent parameters which will be implemented in the LHCb VELO cluster position software tools.

  4. Study on photon sensitivity of silicon diodes related to materials used for shielding

    International Nuclear Information System (INIS)

    Moiseev, T.

    1999-01-01

    Large area silicon diodes used in electronic neutron dosemeters have a significant over-response to X- and gamma-rays, highly non-linear at photon energies below 200 keV. This over-response to photons is proportional to the diode's active area and strongly affects the neutron sensitivity of such dosemeters. Since silicon diodes are sensitive to light and electromagnetic fields, most diode detector assemblies are provided with a shielding, sometimes also used as radiation filter. In this paper, the influence of materials covering the diode's active area is investigated using the MCNP-4A code by estimating the photon induced pulses in a typical silicon wafer (300 μm thickness and 1 cm diameter) when provided with a front case cover. There have been simulated small-size diode front covers made of several materials with low neutron interaction cross-sections like aluminium, TEFLON, iron and lead. The estimated number of induced pulses in the silicon wafer is calculated for each type of shielding at normal photon incidence for several photon energies from 9.8 keV up to 1.15 MeV and compared with that in a bare silicon wafer. The simulated pulse height spectra show the origin of the photon-induced pulses in silicon for each material used as protective cover: the photoelectric effect for low Z front case materials at low-energy incident photons (up to about 65 keV) and the Compton and build-up effects for high Z case materials at higher photon energies. A simple means to lower and flatten the photon response of silicon diodes over an extended X- and gamma rays energy range is proposed by designing a composed photon filter. (author)

  5. Study on Photon Sensitivity of Silicon Diodes Related to Materials Used for Shielding

    International Nuclear Information System (INIS)

    Moiseev, T.

    2000-01-01

    Large area Silicon diodes used in electronic neutron dosemeters have a significant over-response to X and gamma rays, highly non-linear at photon energies below 200 keV. This over-response to photons is proportional to the diodes active area and strongly affects the neutron sensitivity of such dosemeters. Since Silicon diodes are sensitive to light and electromagnetic fields, most diode detector assemblies are provided with a shielding, sometimes also used as radiation filter. In this paper, the influence of materials covering the diode's active area is investigated using the MCNP-4A code by estimating the photon induced pulses in a typical silicon wafer (300 μm thickness and 1 cm diameter) when provided with a front case cover. There have been simulated small-size diode front covers made of several materials with low neutron interaction cross-sections like aluminium, TEFLON, iron and lead. The estimated number of induced pulses in the silicon wafer is calculated for each type of shielding at normal photon incidence for several photon energies from 9.8 keV up to 1.15 MeV and compared with that in a bare silicon wafer. The simulated pulse height spectra show the origin of the photon induced pulses in silicon for each material used as protective cover: the photoelectric effect for low Z front case materials at low energy incident photons (up to about 65 keV) and the Compton and build-up effects for high Z case materials at higher photon energies. A simple means to lower and flatten the photon response of silicon diodes over an extended X and gamma rays energy range is proposed by designing a composed photon filter. (author)

  6. Scintillating fibre detectors using position-sensitive photomultipliers

    International Nuclear Information System (INIS)

    Agoritsas, V.; Bergdolt, A.M.; Bing, O.; Bravar, A.; Ditta, J.; Drevenak, R.

    1995-01-01

    Scintillating fibre technology has made substantial progress, and has demonstrated great potential for fast tracking and triggering in high luminosity experiments in Particle Physics. Some recent issues of the RD-17 project at CERN are presented for fast and precise readout of scintillating fibre arrays, as well as for upgrade of position-sensitive photomultipliers. Excellent matching of the scintillating fibre and the position-sensitive photomultiplier, in particular in time characteristics, allowed to achieve excellent detector performances, typically a spatial resolution of ∼ 125 μm with time resolution better than 1 ns and detection efficiency greater than 95%. (author)10 refs.; 25 figs.; 1 tab

  7. A setup for measurement of beam stability and position using position sensitive detector for Indus-1

    International Nuclear Information System (INIS)

    Nathwani, R.K.; Joshi, D.K.; Tyagi, Y.; Soni, R.S.; Puntambekar, T.A.; Pithawa, C.K.

    2009-01-01

    The 450 MeV electron synchrotron radiation source Indus-1 is operational at RRCAT. A set-up has been developed to measure the relative transverse positional stability of the electron beam and its position with microns resolution using position sensitive photodiodes. The set-up has been installed at the diagnostics beam line of Indus-1. Synchrotron light from photo physics beamline was reflected out by inserting a Ni coated mirror and was focused onto a duo-lateral position sensitive photodiode by using two mirrors of 1.25 meter focal length to obtain unity magnification. The set-up consists of a duo-lateral position sensitive detector (PSD), precision processing electronics and a PC based data acquisition system. A computer program captures the processed signals on to a PC using GPIB interface and displays vertical position of the beam in real time. The paper describes the salient features of the setup developed for measurement of beam stability. (author)

  8. A silicon integrated micro nano-positioning XY-stage for nano-manipulation

    International Nuclear Information System (INIS)

    Sun Lining; Wang Jiachou; Rong Weibin; Li Xinxin; Bao Haifei

    2008-01-01

    An integrated micro XY-stage with a 2 × 2 mm 2 movable table is designed and fabricated for application in nanometer-scale operation and nanometric positioning precision. The device integrates the functions of both actuating and sensing in a monolithic chip and is mainly composed of a silicon-based XY-stage, comb-drive actuator and a displacement sensor, which are developed by using double-sided bulk-micromachining technology. The high-aspect-ratio comb-driven XY-stage is achieved by deep reactive ion etching (DRIE) on both sides of the wafer. The displacement sensor is formed on four vertical sidewall surface piezoresistors with a full Wheatstone bridge circuit, where a novel fabrication process of a vertical sidewall surface piezoresistor is proposed. Comprehensive design and analysis of the comb actuator, the piezoresistive displacement sensor and the XY-stage are given in full detail, and the experimental results verify the design and fabrication of the device. The final realization of the device shows that the sensitivity of the fabricated piezoresistive sensors is better than 1.17 mV µm −1 without amplification, and the linearity is better than 0.814%. Under 28.5 V driving voltage, a ±10 µm single-axis displacement is measured without crosstalk and the resonant frequency is measured at 983 Hz in air

  9. Amorphous Silicon Position Detectors for the Link Alignment System of the CMS Detector: Users Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, A.; Gomez, G.; Gonzalez-Sanchez, F. J.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Ruiz-Arbol, P.; Scodellaro, L.; Vila, I.; Virto, A. L.; Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M. I.; Molinero, A.; Navarrete, J.; Oller, J. C.; Yuste, C.

    2007-07-01

    We present the general characteristics, calibration procedures and measured performance of the Amorphous Silicon Position Detectors installed in the Link Alignment System of the CMS Detector for laser beam detection and reconstruction and give the Data Base to be used as a Handbook during CMS operation. (Author) 10 refs.

  10. Amorphous Silicon Position Detectors for the Link Alignment System of the CMS Detector: Users Handbook

    International Nuclear Information System (INIS)

    Calderon, A.; Gomez, G.; Gonzalez-Sanchez, F. J.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Ruiz-Arbol, P.; Scodellaro, L.; Vila, I.; Virto, A. L.; Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M. I.; Molinero, A.; Navarrete, J.; Oller, J. C.; Yuste, C.

    2007-01-01

    We present the general characteristics, calibration procedures and measured performance of the Amorphous Silicon Position Detectors installed in the Link Alignment System of the CMS Detector for laser beam detection and reconstruction and give the Data Base to be used as a Handbook during CMS operation. (Author) 10 refs

  11. Construction process and read-out electronics of amorphous silicon position detectors for multipoint alignment monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, C.; Schubert, M.B.; Lutz, B.; Werner, J.H. [Steinbeis-Transferzentrum fuer Angewandte Photovoltaik und Duennschichttechnik, Stuttgart (Germany); Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E. [CIEMAT, Madrid (Spain); Ferrando, A. [CIEMAT, Madrid (Spain)], E-mail: antonio.ferrando@ciemat.es; Josa, M.I.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C. [CIEMAT, Madrid (Spain); Calderon, A.; Fernandez, M.G.; Gomez, G.; Gonzalez-Sanchez, F.J.; Martinez-Rivero, C.; Matorras, F. [Instituto de Fisica de Cantabria IFCA/CSIC-University of Cantabria, Santander (Spain)] (and others)

    2009-09-01

    We describe the construction process of large-area high-performance transparent amorphous silicon position detecting sensors. Details about the characteristics of the associated local electronic board (LEB), specially designed for these sensors, are given. In addition we report on the performance of a multipoint alignment monitoring application of 12 sensors in a 13 m long light path.

  12. Multipoint alignment monitoring with amorphous silicon position detectors in a complex light path

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E. [CIEMAT, Madrid (Spain); Ferrando, A., E-mail: antonio.ferrando@ciemat.e [CIEMAT, Madrid (Spain); Josa, M.I.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C. [CIEMAT, Madrid (Spain); Calderon, A.; Gomez, G.; Gonzalez-Sanchez, F.J.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Ruiz-Arbol, P.; Sobron, M.; Vila, I.; Virto, A.L. [Instituto de Fisica de Cantabria. CSIC-University of Cantabria, Santander (Spain)

    2010-12-01

    This document presents an application of the new generation of amorphous silicon position detecting (ASPD) sensors to multipoint alignment. Twelve units are monitored along a 20 m long laser beam, where the light path is deflected by 90{sup o} using a pentaprism.

  13. Multipoint alignment monitoring with amorphous silicon position detectors in a complex light path

    International Nuclear Information System (INIS)

    Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C.; Calderon, A.; Gomez, G.; Gonzalez-Sanchez, F.J.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Ruiz-Arbol, P.; Sobron, M.; Vila, I.; Virto, A.L.

    2010-01-01

    This document presents an application of the new generation of amorphous silicon position detecting (ASPD) sensors to multipoint alignment. Twelve units are monitored along a 20 m long laser beam, where the light path is deflected by 90 o using a pentaprism.

  14. Sensitivity of GRETINA position resolution to hole mobility

    Energy Technology Data Exchange (ETDEWEB)

    Prasher, V.S. [Department of Physics, University of Massachusetts Lowell, Lowell, MA 01854 (United States); Cromaz, M. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Merchan, E.; Chowdhury, P. [Department of Physics, University of Massachusetts Lowell, Lowell, MA 01854 (United States); Crawford, H.L. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Lister, C.J. [Department of Physics, University of Massachusetts Lowell, Lowell, MA 01854 (United States); Campbell, C.M.; Lee, I.Y.; Macchiavelli, A.O. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Radford, D.C. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Wiens, A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2017-02-21

    The sensitivity of the position resolution of the gamma-ray tracking array GRETINA to the hole charge-carrier mobility parameter is investigated. The χ{sup 2} results from a fit of averaged signal (“superpulse”) data exhibit a shallow minimum for hole mobilities 15% lower than the currently adopted values. Calibration data on position resolution is analyzed, together with simulations that isolate the hole mobility dependence of signal decomposition from other effects such as electronics cross-talk. The results effectively exclude hole mobility as a dominant parameter for improving the position resolution for reconstruction of gamma-ray interaction points in GRETINA.

  15. Overview of CMS robotic silicon module assembly hardware based on Aerotech Gantry Positioning system.

    CERN Multimedia

    Honma, Alan

    1999-01-01

    The goal of the robotic silicon module assembly pilot project is to fully automate the gluing and pick and placement of silicon sensors and front-end hybrid onto a carbon-fibre frame. The basis for thesystem is the Aerotech Gantry Positioning System (AGS10000) machineshown in the centre of the picture. To the left is the PC which contains the controller card and runs the user interface. To the rightis the rack of associated electronics which interfaces with the CERNbuilt tooling and vacuum chuck system.

  16. Sensitivity encoded silicon photomultiplier—a new sensor for high-resolution PET-MRI

    International Nuclear Information System (INIS)

    Schulz, Volkmar; Berker, Yannick; Berneking, Arne; Omidvari, Negar; Kiessling, Fabian; Gola, Alberto; Piemonte, Claudio

    2013-01-01

    Detectors for simultaneous positron emission tomography and magnetic resonance imaging in particular with sub-mm spatial resolution are commonly composed of scintillator crystal arrays, readout via arrays of solid state sensors, such as avalanche photo diodes (APDs) or silicon photomultipliers (SiPMs). Usually a light guide between the crystals and the sensor is used to enable the identification of crystals which are smaller than the sensor elements. However, this complicates crystal identification at the gaps and edges of the sensor arrays. A solution is to use as many sensors as crystals with a direct coupling, which unfortunately increases the complexity and power consumption of the readout electronics. Since 1997, position-sensitive APDs have been successfully used to identify sub-mm crystals. Unfortunately, these devices show a limitation in their time resolution and a degradation of spatial resolution when placed in higher magnetic fields. To overcome these limitations, this paper presents a new sensor concept that extends conventional SiPMs by adding position information via the spatial encoding of the channel sensitivity. The concept allows a direct coupling of high-resolution crystal arrays to the sensor with a reduced amount of readout channels. The theory of sensitivity encoding is detailed and linked to compressed sensing to compute unique sparse solutions. Two devices have been designed using one- and two-dimensional linear sensitivity encoding with eight and four readout channels, respectively. Flood histograms of both devices show the capability to precisely identify all 4 × 4 LYSO crystals with dimensions of 0.93 × 0.93 × 10 mm 3 . For these crystals, the energy and time resolution (MV ± SD) of the devices with one (two)-dimensional encoding have been measured to be 12.3 · (1 ± 0.047)% (13.7 · (1 ± 0.047)%) around 511 keV with a paired coincidence time resolution (full width at half maximum) of 462 · (1 ± 0.054) ps (452 · (1 ± 0

  17. Sensitivity encoded silicon photomultiplier—a new sensor for high-resolution PET-MRI

    Science.gov (United States)

    Schulz, Volkmar; Berker, Yannick; Berneking, Arne; Omidvari, Negar; Kiessling, Fabian; Gola, Alberto; Piemonte, Claudio

    2013-07-01

    Detectors for simultaneous positron emission tomography and magnetic resonance imaging in particular with sub-mm spatial resolution are commonly composed of scintillator crystal arrays, readout via arrays of solid state sensors, such as avalanche photo diodes (APDs) or silicon photomultipliers (SiPMs). Usually a light guide between the crystals and the sensor is used to enable the identification of crystals which are smaller than the sensor elements. However, this complicates crystal identification at the gaps and edges of the sensor arrays. A solution is to use as many sensors as crystals with a direct coupling, which unfortunately increases the complexity and power consumption of the readout electronics. Since 1997, position-sensitive APDs have been successfully used to identify sub-mm crystals. Unfortunately, these devices show a limitation in their time resolution and a degradation of spatial resolution when placed in higher magnetic fields. To overcome these limitations, this paper presents a new sensor concept that extends conventional SiPMs by adding position information via the spatial encoding of the channel sensitivity. The concept allows a direct coupling of high-resolution crystal arrays to the sensor with a reduced amount of readout channels. The theory of sensitivity encoding is detailed and linked to compressed sensing to compute unique sparse solutions. Two devices have been designed using one- and two-dimensional linear sensitivity encoding with eight and four readout channels, respectively. Flood histograms of both devices show the capability to precisely identify all 4 × 4 LYSO crystals with dimensions of 0.93 × 0.93 × 10 mm3. For these crystals, the energy and time resolution (MV ± SD) of the devices with one (two)-dimensional encoding have been measured to be 12.3 · (1 ± 0.047)% (13.7 · (1 ± 0.047)%) around 511 keV with a paired coincidence time resolution (full width at half maximum) of 462 · (1 ± 0.054) ps (452 · (1 ± 0

  18. Sensitivity encoded silicon photomultiplier--a new sensor for high-resolution PET-MRI.

    Science.gov (United States)

    Schulz, Volkmar; Berker, Yannick; Berneking, Arne; Omidvari, Negar; Kiessling, Fabian; Gola, Alberto; Piemonte, Claudio

    2013-07-21

    Detectors for simultaneous positron emission tomography and magnetic resonance imaging in particular with sub-mm spatial resolution are commonly composed of scintillator crystal arrays, readout via arrays of solid state sensors, such as avalanche photo diodes (APDs) or silicon photomultipliers (SiPMs). Usually a light guide between the crystals and the sensor is used to enable the identification of crystals which are smaller than the sensor elements. However, this complicates crystal identification at the gaps and edges of the sensor arrays. A solution is to use as many sensors as crystals with a direct coupling, which unfortunately increases the complexity and power consumption of the readout electronics. Since 1997, position-sensitive APDs have been successfully used to identify sub-mm crystals. Unfortunately, these devices show a limitation in their time resolution and a degradation of spatial resolution when placed in higher magnetic fields. To overcome these limitations, this paper presents a new sensor concept that extends conventional SiPMs by adding position information via the spatial encoding of the channel sensitivity. The concept allows a direct coupling of high-resolution crystal arrays to the sensor with a reduced amount of readout channels. The theory of sensitivity encoding is detailed and linked to compressed sensing to compute unique sparse solutions. Two devices have been designed using one- and two-dimensional linear sensitivity encoding with eight and four readout channels, respectively. Flood histograms of both devices show the capability to precisely identify all 4 × 4 LYSO crystals with dimensions of 0.93 × 0.93 × 10 mm(3). For these crystals, the energy and time resolution (MV ± SD) of the devices with one (two)-dimensional encoding have been measured to be 12.3 · (1 ± 0.047)% (13.7 · (1 ± 0.047)%) around 511 keV with a paired coincidence time resolution (full width at half maximum) of 462 · (1 ± 0.054) ps (452 · (1 ± 0

  19. POSSuMUS. A position sensitive scintillating muon SiPM detector

    International Nuclear Information System (INIS)

    Ruschke, Alexander

    2014-01-01

    The development of a modular designed large scale scintillation detector with a two-dimensional position sensitivity is presented in this thesis. This novel POsition Sensitive Scintillating MUon SiPM Detector is named POSSuMUS. The POSSuMUS detector is capable to determine the particle's position in two space dimensions with a fast trigger capability. Each module is constructed from two trapezoidal shaped plastic scintillators to form one rectangular shaped detector module. Both trapezoids are optically insulated against each other. In both trapezoids the scintillation light is collected by plastic fibers and guided towards silicon photomultipliers (SiPMs). SiPMs are light sensors which are capable to detect even smallest amounts of light. By combining several detector modules, position sensitive areas from 100 cm 2 to few m 2 are achievable with few readout channels. Therefore, POSSuMUS provides a cost effective detector concept. The position sensitivity along the trapezoidal geometry of one detector module is achieved by the path length dependent amount of detected light for crossing particles. The ratio of the light yields in both trapezoids is calculated. This value corresponds to the position of the particle traversing the detector. A spatial resolution in the order of several mm is foreseen. The position sensitivity along the scintillator module is determined by the propagation time of light to the SiPMs located on opposite sides of the detector. A spatial resolution of few cm is expected for this direction. The POSSuMUS detector is applicable as large area trigger detector with a two dimensional position information of crossing particles. This is suitable in detector tests of large area precesion detectors or for measuring the small angle scattering of cosmic muons. At the beginning of this thesis, the determination of important SiPM characteristics like the breakdown voltage is presented. In the course of this work the detector principle is proven by

  20. Charge-sensitive preamplifier IC for silicon calorimetry at colliders

    International Nuclear Information System (INIS)

    Baturitsky, M.A.; Chekhovsky, V.A.; Emel'yanchik, I.F.; Shumeiko, N.M.; Golutvin, I.A.; Zamyatin, N.I.; Dvornikov, O.V.

    1995-01-01

    Four versions of a fast monolithic charge-sensitive preamplifier (CSP) were designed using microwave BJT-JFET technology. The best one has a 3.5 ns rise time for input detector capacitance C d =100 pF and approximately 8 mW power dissipation for 5 V supply voltage. The ENC performance at shaping time 30 ns is 1350 e+17 e/pF for C d up to 600 pF. Crosstalk in a four-channel amplifier made in the same chip was measured to be about -46 dB for C d =100 pF. The linear output voltage swing is 0.8 V for voltage supply 5 V. The IC has revealed good radiation hardness to neutron irradiation. ((orig.))

  1. Enhancing the far-UV sensitivity of silicon CMOS imaging arrays

    Science.gov (United States)

    Retherford, K. D.; Bai, Yibin; Ryu, Kevin K.; Gregory, J. A.; Welander, Paul B.; Davis, Michael W.; Greathouse, Thomas K.; Winter, Gregory S.; Suntharalingam, Vyshnavi; Beletic, James W.

    2014-07-01

    We report our progress toward optimizing backside-illuminated silicon PIN CMOS devices developed by Teledyne Imaging Sensors (TIS) for far-UV planetary science applications. This project was motivated by initial measurements at Southwest Research Institute (SwRI) of the far-UV responsivity of backside-illuminated silicon PIN photodiode test structures described in Bai et al., SPIE, 2008, which revealed a promising QE in the 100-200 nm range as reported in Davis et al., SPIE, 2012. Our effort to advance the capabilities of thinned silicon wafers capitalizes on recent innovations in molecular beam epitaxy (MBE) doping processes. Key achievements to date include: 1) Representative silicon test wafers were fabricated by TIS, and set up for MBE processing at MIT Lincoln Laboratory (LL); 2) Preliminary far-UV detector QE simulation runs were completed to aid MBE layer design; 3) Detector fabrication was completed through the pre-MBE step; and 4) Initial testing of the MBE doping process was performed on monitoring wafers, with detailed quality assessments. Early results suggest that potential challenges in optimizing the UV-sensitivity of silicon PIN type CMOS devices, compared with similar UV enhancement methods established for CCDs, have been mitigated through our newly developed methods. We will discuss the potential advantages of our approach and briefly describe future development steps.

  2. Performance comparison between silicon solar panel and dye-sensitized solar panel in Malaysia

    Science.gov (United States)

    Hamed, N. K. A.; Ahmad, M. K.; Urus, N. S. T.; Mohamad, F.; Nafarizal, N.; Ahmad, N.; Soon, C. F.; Ameruddin, A. S.; Faridah, A. B.; Shimomura, M.; Murakami, K.

    2017-09-01

    In carrying out experimental research in performance between silicon solar panel and dye-sensitive solar panel, we have been developing a device and a system. This system has been developed consisting of controllers, hardware and software. This system is capable to get most of the input sources. If only need to change the main circuit and coding for a different source input value. This device is able to get the ambient temperature, surface temperature, surrounding humidity, voltage with load, current with load, voltage without load and current without load and save the data into external memory. This device is able to withstand the heat and rain as it was fabricated in a waterproof box. This experiment was conducted to examine the performance of both the solar panels which are capable to maintain their stability and performance. A conclusion based on data populated, the distribution of data for dye-sensitized solar panel is much better than silicon solar panel as dye-sensitized solar panel is very sensitive to heat and not depend only on midday where is that is the maximum ambient temperature for both solar panel as silicon solar panel only can give maximum and high output only when midday.

  3. Position sensitivity of the first SmartPET HPGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, R.J. [Department of Physics, University of Liverpool, Liverpool (United Kingdom)]. E-mail: rjc@ns.ph.liv.ac.uk; Turk, G. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Boston, A.J. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Boston, H.C. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Cresswell, J.R. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Mather, A.R. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Nolan, P.J. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Hall, C.J. [CCLRC Daresbury, Warrington, Cheshire (United Kingdom); Lazarus, I. [CCLRC Daresbury, Warrington, Cheshire (United Kingdom); Simpson, J. [CCLRC Daresbury, Warrington, Cheshire (United Kingdom); Berry, A. [School of Physics and materials Engineering, Monash University, Melbourne (Australia); Beveridge, T. [School of Physics and materials Engineering, Monash University, Melbourne (Australia); Gillam, J. [School of Physics and materials Engineering, Monash University, Melbourne (Australia); Lewis, R.A. [School of Physics and materials Engineering, Monash University, Melbourne (Australia)

    2007-04-01

    In this paper we discuss the Smart Positron Emission Tomography (PET) imaging system being developed by University of Liverpool in conjunction with CCLRC Daresbury Laboratory. We describe the motivation for the development of a semiconductor-based PET system and the advantages it will offer over current tomographs. Details of the detectors and associated electronics are discussed and results of high precision scans are presented. Analysis of this scan data has facilitated full characterization of the detector response function and calibration of the three-dimensional position sensitivity. This work presents the analysis of the depth sensitivity of the detector.

  4. Depression reduces perceptual sensitivity for positive words and pictures.

    Science.gov (United States)

    Atchley, Ruth Ann; Ilardi, Stephen S; Young, Keith M; Stroupe, Natalie N; O'Hare, Aminda J; Bistricky, Steven L; Collison, Elizabeth; Gibson, Linzi; Schuster, Jonathan; Lepping, Rebecca J

    2012-01-01

    There is evidence of maladaptive attentional biases for lexical information (e.g., Atchley, Ilardi, & Enloe, 2003; Atchley, Stringer, Mathias, Ilardi, & Minatrea, 2007) and for pictographic stimuli (e.g., Gotlib, Krasnoperova, Yue, & Joormann, 2004) among patients with depression. The current research looks for depressotypic processing biases among depressed out-patients and non-clinical controls, using both verbal and pictorial stimuli. A d' measure (sensitivity index) was used to examine each participant's perceptual sensitivity threshold. Never-depressed controls evidenced a detection bias for positive picture stimuli, while depressed participants had no such bias. With verbal stimuli, depressed individuals showed specific decrements in the detection of positive person-referent words (WINNER), but not with positive non-person-referent words (SUNSHINE) or with negative words. Never-depressed participants showed no such differences across word types. In the current study, depression is characterised both by an absence of the normal positivistic biases seen in individuals without mood disorders (consistent with McCabe & Gotlib, 1995), and by a specific reduction in sensitivity for person-referent positive information that might be inconsistent with depressotypic self-schemas.

  5. Optical temperature sensor with enhanced sensitivity by employing hybrid waveguides in a silicon Mach-Zehnder interferometer

    DEFF Research Database (Denmark)

    Guan, Xiaowei; Wang, Xiaoyan; Frandsen, Lars Hagedorn

    2016-01-01

    We report on a novel design of an on-chip optical temperature sensor based on a Mach-Zehnder interferometer configuration where the two arms consist of hybrid waveguides providing opposite temperature-dependent phase changes to enhance the temperature sensitivity of the sensor. The sensitivity...... of the fabricated sensor with silicon/polymer hybrid waveguides is measured to be 172 pm/°C, which is two times larger than a conventional all-silicon optical temperature sensor (∼80 pm/°C). Moreover, a design with silicon/titanium dioxide hybrid waveguides is by calculation expected to have a sensitivity as high...

  6. Highly Sensitive Bulk Silicon Chemical Sensors with Sub-5 nm Thin Charge Inversion Layers.

    Science.gov (United States)

    Fahad, Hossain M; Gupta, Niharika; Han, Rui; Desai, Sujay B; Javey, Ali

    2018-03-27

    There is an increasing demand for mass-producible, low-power gas sensors in a wide variety of industrial and consumer applications. Here, we report chemical-sensitive field-effect-transistors (CS-FETs) based on bulk silicon wafers, wherein an electrostatically confined sub-5 nm thin charge inversion layer is modulated by chemical exposure to achieve a high-sensitivity gas-sensing platform. Using hydrogen sensing as a "litmus" test, we demonstrate large sensor responses (>1000%) to 0.5% H 2 gas, with fast response (<60 s) and recovery times (<120 s) at room temperature and low power (<50 μW). On the basis of these performance metrics as well as standardized benchmarking, we show that bulk silicon CS-FETs offer similar or better sensing performance compared to emerging nanostructures semiconductors while providing a highly scalable and manufacturable platform.

  7. Amorphous Silicon-Germanium Films with Embedded Nano crystals for Thermal Detectors with Very High Sensitivity

    International Nuclear Information System (INIS)

    Calleja, C.; Torres, A.; Rosales-Quintero, P.; Moreno, M.

    2016-01-01

    We have optimized the deposition conditions of amorphous silicon-germanium films with embedded nano crystals in a plasma enhanced chemical vapor deposition (PECVD) reactor, working at a standard frequency of 13.56 MHz. The objective was to produce films with very large Temperature Coefficient of Resistance (TCR), which is a signature of the sensitivity in thermal detectors (micro bolometers). Morphological, electrical, and optical characterization were performed in the films, and we found optimal conditions for obtaining films with very high values of thermal coefficient of resistance (TCR = 7.9%K -1 ). Our results show that amorphous silicon-germanium films with embedded nano crystals can be used as thermo sensitive films in high performance infrared focal plane arrays (IRFPAs) used in commercial thermal cameras.

  8. Position-sensitive gaseous photomultipliers research and applications

    CERN Document Server

    Francke, Tom; Peskov, Vladimir

    2016-01-01

    Gaseous photomultipliers are defined as gas-filled devices capable of recording single ultraviolet (UV) and visible photons with high position resolution. Used in a variety of research areas, these detectors can be paired with computers to treat and store imaging information of UV-light. Position-Sensitive Gaseous Photomultipliers: Research and Applications explores the advancement of gaseous detectors as applied for single photon detection. Emphasizing emerging perspectives and new ways to apply gaseous detectors across research fields, this research-based publication is an essential reference source for engineers, physicists, graduate-level students, and researchers.

  9. Cylinder gauge measurement using a position sensitive detector

    International Nuclear Information System (INIS)

    St John, W. Doyle

    2007-01-01

    A position sensitive detector (PSD) has been used to determine the diameter of cylindrical pins based on the shift in a laser beam's centroid. The centroid of the light beam is defined here as the weighted average of position by the local intensity. A shift can be observed in the centroid of an otherwise axially symmetric light beam, which is partially obstructed. Additionally, the maximum shift in the centroid is a unique function of the obstructing cylinder diameter. Thus to determine the cylinder diameter, one only needs to detect this maximum shift as the cylinder is swept across the beam

  10. Structural Investigations using a position sensitive Neutron Detector

    International Nuclear Information System (INIS)

    Fruchart, D.; Anne, M.; Wolfers, P.; Lartigue, C.; Roudaut, E.

    1986-01-01

    In the accurate determination of the location of lights atoms such as hydrogen in a metal matrix, several types of difficulty may be encountered. Experimentally, neutron diffraction is the most convenient method for such a structure determination. The use of Position Sensitive Detectors is discussed, and selected examples illustrate the advantages and drawbacks of this type of instrument. Judging from present results, significant improvements in recording technique, data collection and reduction, and structure refinement may be obtained in the near future

  11. A novel method for assessing position-sensitive detector performance

    International Nuclear Information System (INIS)

    Clinthorne, N.H.; Rogers, W.L.; Shao, L.; Hero, A.O. III; Koral, K.F.

    1989-01-01

    A marked point process model of a position-sensitive detector is developed which includes the effects of detector efficiency, spatial response, energy response, and source statistics. The average mutual information between the incident distribution of γ rays and the detector response is derived and used as a performance index for detector optimization. A brief example is presented which uses this figure-of-merit for optimization of light guide dimensions for a modular scintillation camera

  12. Light Enhanced Hydrofluoric Acid Passivation: A Sensitive Technique for Detecting Bulk Silicon Defects

    Science.gov (United States)

    Grant, Nicholas E.

    2016-01-01

    A procedure to measure the bulk lifetime (>100 µsec) of silicon wafers by temporarily attaining a very high level of surface passivation when immersing the wafers in hydrofluoric acid (HF) is presented. By this procedure three critical steps are required to attain the bulk lifetime. Firstly, prior to immersing silicon wafers into HF, they are chemically cleaned and subsequently etched in 25% tetramethylammonium hydroxide. Secondly, the chemically treated wafers are then placed into a large plastic container filled with a mixture of HF and hydrochloric acid, and then centered over an inductive coil for photoconductance (PC) measurements. Thirdly, to inhibit surface recombination and measure the bulk lifetime, the wafers are illuminated at 0.2 suns for 1 min using a halogen lamp, the illumination is switched off, and a PC measurement is immediately taken. By this procedure, the characteristics of bulk silicon defects can be accurately determined. Furthermore, it is anticipated that a sensitive RT surface passivation technique will be imperative for examining bulk silicon defects when their concentration is low (<1012 cm-3). PMID:26779939

  13. Compton imaging with a highly-segmented, position-sensitive HPGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Steinbach, T.; Hirsch, R.; Reiter, P.; Birkenbach, B.; Bruyneel, B.; Eberth, J.; Hess, H.; Lewandowski, L. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Gernhaeuser, R.; Maier, L.; Schlarb, M.; Weiler, B.; Winkel, M. [Technische Universitaet Muenchen, Physik Department, Garching (Germany)

    2017-02-15

    A Compton camera based on a highly-segmented high-purity germanium (HPGe) detector and a double-sided silicon-strip detector (DSSD) was developed, tested, and put into operation; the origin of γ radiation was determined successfully. The Compton camera is operated in two different modes. Coincidences from Compton-scattered γ-ray events between DSSD and HPGe detector allow for best angular resolution; while the high-efficiency mode takes advantage of the position sensitivity of the highly-segmented HPGe detector. In this mode the setup is sensitive to the whole 4π solid angle. The interaction-point positions in the 36-fold segmented large-volume HPGe detector are determined by pulse-shape analysis (PSA) of all HPGe detector signals. Imaging algorithms were developed for each mode and successfully implemented. The angular resolution sensitively depends on parameters such as geometry, selected multiplicity and interaction-point distances. Best results were obtained taking into account the crosstalk properties, the time alignment of the signals and the distance metric for the PSA for both operation modes. An angular resolution between 13.8 {sup circle} and 19.1 {sup circle}, depending on the minimal interaction-point distance for the high-efficiency mode at an energy of 1275 keV, was achieved. In the coincidence mode, an increased angular resolution of 4.6 {sup circle} was determined for the same γ-ray energy. (orig.)

  14. Position-Sensitive Organic Scintillation Detectors for Nuclear Material Accountancy

    International Nuclear Information System (INIS)

    Hausladen, P.; Newby, J.; Blackston, M.

    2015-01-01

    Recent years have seen renewed interest in fast organic scintillators with pulse shape properties that enable neutron-gamma discrimination, in part because of the present shortage of He3, but primarily because of the diagnostic value of timing and pulse height information available from such scintillators. Effort at Oak Ridge National Laboratory (ORNL) associated with fast organic scintillators has concentrated on development of position-sensitive fast-neutron detectors for imaging applications. Two aspects of this effort are of interest. First, the development has revisited the fundamental limitations on pulseshape measurement imposed by photon counting statistics, properties of the scintillator, and properties of photomultiplier amplification. This idealized limit can then be used to evaluate the performance of the detector combined with data acquisition and analysis such as free-running digitizers with embedded algorithms. Second, the development of position sensitive detectors has enabled a new generation of fast-neutron imaging instruments and techniques with sufficient resolution to give new capabilities relevant to safeguards. Toward this end, ORNL has built and demonstrated a number of passive and active fast-neutron imagers, including a proof-of-concept passive imager capable of resolving individual fuel pins in an assembly via their neutron emanations. This presentation will describe the performance and construction of position-sensing fast-neutron detectors and present results of imaging measurements. (author)

  15. VUV-sensitive silicon-photomultipliers for the nEXO-experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wrede, Gerrit; Bayerlein, Reimund; Hufschmidt, Patrick; Jamil, Ako; Schneider, Judith; Wagenpfeil, Michael; Ziegler, Tobias; Hoessl, Juergen; Anton, Gisela; Michel, Thilo [ECAP, Friedrich-Alexander-Universitaet Erlangen-Nuernberg (Germany)

    2016-07-01

    The nEXO (next Enriched Xenon Observatory) experiment will search for the neutrinoless double beta decay of Xe-136 with a liquid xenon TPC (Time ProjectionChamber). The sensitivity of the experiment is related to the energy resolution, which itself depends on the accuracies of the measurements of the amount of drifting electrons and the number of scintillation photons with their wavelength being in the vacuum ultraviolet band. Silicon Photomultipliers (SiPM) shall be used for the detection of the scintillation light, since they can be produced extremely radiopure. Commercially available SiPM do not fulfill all requirements of the nEXO experiment, thus a dedicated development is necessary. To characterize the silicon photomultipliers, we have built a test apparatus for xenon liquefaction, in which a VUV-sensitive photomultiplier tube can be operated together with the SiPM. In this contribution we present our apparatus for the SiPM characterization measurements and our latest results on the test of the silicon photomultipliers for the detection of xenon scintillation light.

  16. Studies of the sensitivity dependence of float zone silicon diodes on gamma absorbed dose

    International Nuclear Information System (INIS)

    Pascoalino, K.C.S.; Santos, T.C. dos; Barbosa, R.F.; Camargo, F. de; Goncalves, J.A.C.; Bueno, C.C.

    2011-01-01

    Full text: Several advantages of silicon diodes which include small size, low cost, high sensitivity and wide availability, make them suitable for dosimetry and for radiation field mapping. However, the small radiation tolerance of ordinary silicon devices has imposed constraints on their application in intense radiation fields such as found in industrial radiation processes. This scenario has been changed with the development of radiation hard silicon devices to be used as track detectors in high-energy physics experiments. Particularly, in this work it is presented the dosimetric results obtained with a batch of nine junction silicon diodes developed, in the framework of CERN RD50 Collaboration, as good candidates for improved radiation hardness. These diodes were produced with 300 micrometer n-type silicon substrate grown by standard float zone technique and processed by the Microelectronics Center of Helsinki University of Technology. The samples irradiation was performed using a Co-60 irradiator (Gammacell 220) which delivers a dose-rate of 2 kGy/h. During the irradiation, the unbiased diodes were connected through low-noise coaxial cables to the input of a KEITHLEY 617 electrometer, in order to monitor the devices photocurrent as a function of the exposure time. To study the response uniformity of the batch of nine diodes as well the sensitivity dependence on the absorbed dose, they were irradiated with different doses from 5 kGy up to 50 kGy. The sensitivity response of each device was investigated through the on-line measurements of the current signals as a function of the exposure time. For doses up to 5 kGy, all diodes exhibited a current decay of almost six percent in comparison with the value registered at the start-time of the irradiation. However, this decrease in the current sensitivity is much smaller than those observed with ordinary diodes for the same absorbed dose. The dose-response curves of the devices were also investigated through the plot

  17. Computed tomography with thermal neutrons and gaseous position sensitive detector

    International Nuclear Information System (INIS)

    Souza, Maria Ines Silvani

    2001-12-01

    A third generation tomographic system using a parallel thermal neutron beam and gaseous position sensitive detector has been developed along three discrete phases. At the first one, X-ray tomographic images of several objects, using a position sensitive detector designed and constructed for this purpose have been obtained. The second phase involved the conversion of that detector for thermal neutron detection, by using materials capable to convert neutrons into detectable charged particles, testing afterwards its performance in a tomographic system by evaluation the quality of the image arising from several test-objects containing materials applicable in the engineering field. High enriched 3 He, replacing the argon-methane otherwise used as filling gas for the X-ray detection, as well as, a gadolinium foil, have been utilized as converters. Besides the pure enriched 3 He, its mixture with argon-methane and later on with propane, have been also tested, in order to evaluate the detector efficiency and resolution. After each gas change, the overall performance of the tomographic system using the modified detector, has been analyzed through measurements of the related parameters. This was done by analyzing the images produced by test-objects containing several materials having well known attenuation coefficients for both thermal neutrons and X-rays. In order to compare the performance of the position sensitive detector as modified to detect thermal neutrons, with that of a conventional BF 3 detector, additional tomographs have been conducted using the last one. The results have been compared in terms of advantages, handicaps and complementary aspects for different kinds of radiation and materials. (author)

  18. Application of position-sensitive detectors to positron imaging

    International Nuclear Information System (INIS)

    Yamashita, Takaji; Uchida, Hiroshi; Watanabe, Mitsuo; Omura, Tomohide

    1994-01-01

    Positron imaging including positron emission tomography (PET) is expected to be a promising tool for basic and clinical research, because it makes possible the study of regional chemistry within multiple organs of the body in living human beings and experimental animals. New schemes of high resolution block detectors have been developed to improve the performance of positron imaging systems, which employ small segments of bismuth germanate (BGO) arrays and position-sensitive photomultiplier tubes (PS-PMT). The coincidence detector resolution of less than 2.0 mm in full width at half maximum was achieved with the detectors, which is very close to the theoretical resolution limit in positron imaging. (author)

  19. Fast readout of scintillating fibres using position-sensitive photomultipliers

    International Nuclear Information System (INIS)

    Agoritsas, V.; Akchurin, N.; Bergdolt, A.M.; Bing, O.; Bravar, A.; Ditta, J.; Dufournaud, J.; Dyachenko, V.A.; Giacomich, R.; Gorin, A.M.; Kuroda, K.; Magaudda, D.; Newsom, C.; Okada, K.; Onel, Y.; Penzo, A.; Rakhmatov, V.Ye.; Rykalin, V.I.; Salvato, G.; Savin, A.A.; Schiavon, P.; Sillou, D.; Solovyov, Yu.A.; Takeutchi, F.; Tareb-Reyes, M.; Vasilchenko, V.G.; Yoshida, T.; Zaychenko, A.A.

    1994-01-01

    Major progress has recently been achieved in the fast readout of scintillating fibres using position-sensitive photomultipliers (PSPMs). Experimental results obtained with commercially available PSPMs already show a space resolution better than 200 μm, a time resolution of about 1.5 ns with a detection efficiency higher than 90%, and the possibility of separating double hits with a minimum distance of ∼3 mm. An upgrade of PSPMs based on new dynode structures is also in progress. Results obtained with one new PSPM prototype in a magnetic field are also presented. (orig.)

  20. Amorphous Silicon-Germanium Films with Embedded Nanocrystals for Thermal Detectors with Very High Sensitivity

    Directory of Open Access Journals (Sweden)

    Cesar Calleja

    2016-01-01

    Full Text Available We have optimized the deposition conditions of amorphous silicon-germanium films with embedded nanocrystals in a plasma enhanced chemical vapor deposition (PECVD reactor, working at a standard frequency of 13.56 MHz. The objective was to produce films with very large Temperature Coefficient of Resistance (TCR, which is a signature of the sensitivity in thermal detectors (microbolometers. Morphological, electrical, and optical characterization were performed in the films, and we found optimal conditions for obtaining films with very high values of thermal coefficient of resistance (TCR = 7.9% K−1. Our results show that amorphous silicon-germanium films with embedded nanocrystals can be used as thermosensitive films in high performance infrared focal plane arrays (IRFPAs used in commercial thermal cameras.

  1. Improved performance of silicon-nanoparticle film-coated dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Ravindra Kumar; Bedja, Idriss M. [CRC, Department of Optometry, College of Applied Medical Sciences, King Saud University, P.O. Box 10219, Riyadh 11433 (Saudi Arabia); Aldwayyan, Abdullah Saleh [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

    2012-11-15

    Silicon (Si) nanoparticles with average size of 13 nm and orange-red luminescence under UV absorption were synthesized using electrochemical etching of silicon wafers. A film of Si nanoparticles with thickness of 0.75 {mu}m to 2.6 {mu}m was coated on the glass (TiO{sub 2} side) of a dye-sensitized solar cell (DSSC). The cell exhibited nearly 9% enhancement in power conversion efficiency ({eta}) at film thickness of {proportional_to}2.4 {mu}m under solar irradiation of 100 mW/cm{sup 2} (AM 1.5) with improved fill factor and short-circuit current density. This study revealed for the first time that the Si-nanoparticle film converting UV into visible light and helping in homogeneous irradiation, can be utilized for improving the efficiency of the DSSCs. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Emulation workbench for position sensitive gaseous scintillation detectors

    International Nuclear Information System (INIS)

    Pereira, L.; Margato, L.M.S.; Morozov, A.; Solovov, V.; Fraga, F. A. F.

    2015-01-01

    Position sensitive detectors based on gaseous scintillation proportional counters with Anger-type readout are being used in several research areas such as neutron detection, search for dark matter and neutrinoless double beta decay. Design and optimization of such detectors are complex and time consuming tasks. Simulations, while being a powerful tool, strongly depend on the light transfer models and demand accurate knowledge of many parameters, which are often not available. Here we describe an alternative approach based on the experimental evaluation of a detector using an isotropic point-like light source with precisely controllable light emission properties, installed on a 3D positioning system. The results obtained with the developed setup at validation conditions, when the scattered light is strongly suppressed show good agreement with simulations

  3. Beam test of the 2D position sensitive neutron detector

    International Nuclear Information System (INIS)

    Tian Lichao; Chen Yuanbo; Sun Zhijia; Tang Bin; Zhou Jianrong; Qi Huirong; Liu Rongguang; Zhang Jian; Yang Guian; Xu Hong

    2014-01-01

    China Spallation Neutron Source (CSNS), one of the Major scientific apparatuses of the national Eleventh Five-Year Plane, is under construction and three spectrumeters will be constructed in the first phase of the project. A 2D position sensitive neutron detector has been constructed for the Multifunctional Reflect spectrumeter (MR) in Institute of High Energy Physics (IHEP). The basic operation principle of the detector and the test on the residual stress diffractometer of Chinese Advanced Research Reactor (CARR) in China Institute of Atomic Energy (CIAE) is introduced in this paper. The results show that it has a good position resolution of l.18 mm (FWHM) for the neutrons of l.37 A and 2D imaging ability, which is consistent with the theory. It can satisfy the requirements of MR and lays the foundation for the construction of larger neutron detectors. (authors)

  4. Two dimension position sensitive multi-plate PPAC

    International Nuclear Information System (INIS)

    Mao Ruishi; Guo Zhongyan; Xiao Guoqing; Zhan Wenlong; Xu Hushan; Hu Zhengguo; Wang Meng; Sun Zhiyu; Chen Zhiqiang; Chen Lixin; Li Chen; Bai Jie; Zhang Jinxia; Li Cunfan

    2003-01-01

    A two-dimensional positional sensitive multi-plate PPAC with resistance chain readout has been developed for Radioactive Ion Beam Line in Lanzhou (RIBLL). The PPAC has an active area of 100 mm x 100 mm. It consists of an anode plane, a x wire plane, a y wire plane and two cathode planes. The gaps between anode and wire planes are 3 mm. And the gaps between cathodes and wire planes also are 3 mm. When filled with iso-butane at a pressure of 6.5 mb, the 0.58 mm (FWHM) position resolution and >99.2% detection efficiencies and <±50 μm linearity of the PPAC was estimated for 3 components α source

  5. On the origin of increased sensitivity and mass resolution using silicon masks in MALDI.

    Science.gov (United States)

    Diologent, Laurent; Franck, Julien; Wisztorski, Maxence; Treizebre, Anthony; Focsa, Cristian; Fournier, Isabelle; Ziskind, Michael

    2014-02-04

    Since its development, MALDI has proved its performance in the analysis of intact biomolecules up to high molecular weights, regardless of their polarity. Sensitivity of MALDI instruments is a key point for breaking the limits of observing biomolecules of lower abundances. Instrumentation is one way to improve sensitivity by increasing ion transmission and using more sensitive detection systems. On the other side, improving MALDI ion production yields would have important outcomes. MALDI ion production is still not well-controlled and, indeed, the amount of ions produced per laser shot with respect to the total volume of desorbed material is very low. This has particular implications for certain applications, such as MALDI MS imaging where laser beam focusing as fine as possible (5-10 μm) is searched in order to reach higher spatial resolution images. However, various studies point out an intrinsic decrease in signal intensity for strong focusing. We have therefore been interested in developing silicon mask systems to decrease an irradiated area by cutting rather than focusing the laser beam and to study the parameters affecting sensitivity using such systems. For this, we systematically examined variation with laser fluence of intensity and spectral resolution in MALDI of standard peptides when using silicon-etched masks of various aperture sizes. These studies demonstrate a simultaneous increase in spectral resolution and signal intensity. Origin of this effect is discussed in the frame of the two-step ionization model. Experimental data in the low fluence range are fitted with an increase of the primary ionization through matrix-silicon edge contact provided by the masks. On the other hand, behavior at higher fluence could be explained by an effect on the secondary ionization via changes in the plume dynamics.

  6. Modified MIS-structure based on nanoporous silicon with enhanced sensitivity to the hydrogen containing gases

    Energy Technology Data Exchange (ETDEWEB)

    Gorbanyuk, T.; Evtukh, A.; Litovchenko, V.; Solntsev, V. [Institute of Semiconductor Physics, Kiev (Ukraine)

    2008-07-01

    The gas sensitivity of metal-insulator-semiconductor (MIS)-structures based on nanoporous silicon with active electrodes from palladium/tungsten oxide composite has been studied. It was found that the using of palladium/tungsten oxide composite (instead of thin palladium film) leads to enhanced sensitivity of MIS structures to hydrogen sulphide in air. The mechanism of this phenomenon has been established. The enhanced H{sub 2}S sensitivity is explained in the following way. The microparticles of tungsten trioxide inside palladium matrix stimulate the dissociation of hydrogen sulphide molecules, and hydrogen atoms and/or protons flow down to palladium surface, are absorbed by palladium volume, diffuse to palladium/oxidized nanoporous silicon interface. Hydrogen atoms adsorbed at the interface are polarized and give rise to a dipole layer. As a result, the voltage shift of the capacity-voltage (C-V) curve proportional to the measured gas concentration is observed. The surface microstructure of Pd/WO{sub 3} composite was studied by AFM microscopy. The chemical content of the composite film has been investigated by SIMS. It was found that the composite film on nanoporous silicon surface poses the holes with the size about 0.05 {mu}m, the mean separation between tungsten oxide microparticles is 1-2 {mu}m. It also was found that the using of the additional double layer polymer film (polymer film (phthalocyanine zinc)/semicon-ductor film (cadmium sulphide)) on composite film surface leads to the additional enhancement of the gas sensitivity to hydrogen sulphide. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Real-Time and In-Flow Sensing Using a High Sensitivity Porous Silicon Microcavity-Based Sensor

    Directory of Open Access Journals (Sweden)

    Raffaele Caroselli

    2017-12-01

    Full Text Available Porous silicon seems to be an appropriate material platform for the development of high-sensitivity and low-cost optical sensors, as their porous nature increases the interaction with the target substances, and their fabrication process is very simple and inexpensive. In this paper, we present the experimental development of a porous silicon microcavity sensor and its use for real-time in-flow sensing application. A high-sensitivity configuration was designed and then fabricated, by electrochemically etching a silicon wafer. Refractive index sensing experiments were realized by flowing several dilutions with decreasing refractive indices, and measuring the spectral shift in real-time. The porous silicon microcavity sensor showed a very linear response over a wide refractive index range, with a sensitivity around 1000 nm/refractive index unit (RIU, which allowed us to directly detect refractive index variations in the 10−7 RIU range.

  8. Real-Time and In-Flow Sensing Using a High Sensitivity Porous Silicon Microcavity-Based Sensor.

    Science.gov (United States)

    Caroselli, Raffaele; Martín Sánchez, David; Ponce Alcántara, Salvador; Prats Quilez, Francisco; Torrijos Morán, Luis; García-Rupérez, Jaime

    2017-12-05

    Porous silicon seems to be an appropriate material platform for the development of high-sensitivity and low-cost optical sensors, as their porous nature increases the interaction with the target substances, and their fabrication process is very simple and inexpensive. In this paper, we present the experimental development of a porous silicon microcavity sensor and its use for real-time in-flow sensing application. A high-sensitivity configuration was designed and then fabricated, by electrochemically etching a silicon wafer. Refractive index sensing experiments were realized by flowing several dilutions with decreasing refractive indices, and measuring the spectral shift in real-time. The porous silicon microcavity sensor showed a very linear response over a wide refractive index range, with a sensitivity around 1000 nm/refractive index unit (RIU), which allowed us to directly detect refractive index variations in the 10 -7 RIU range.

  9. SENSITIVITY TEMPERATURE DEPENDENCE RESEARCH OF TV-CAMERAS BASED ON SILICON MATRIXES

    Directory of Open Access Journals (Sweden)

    Alexey N. Starchenko

    2017-07-01

    Full Text Available Subject of Research. The research is dedicated to the analysis of sensitivity change patterns of the cameras based on silicon CMOS-matrixes in various ambient temperatures. This information is necessary for the correct camera application for photometric measurements in-situ. The paper deals with studies of sensitivity variations of two digital cameras with different silicon CMOS matrixes in visible and near IR regions of the spectrum at temperature change. Method. Due to practical restrictions the temperature changes were recorded in separate spectral intervals important for practical use of the cameras. The experiments were carried out with the use of a climatic chamber, providing change and keeping the temperature range from minus 40 to plus 50 °C at a pitch of 10 о С. Two cameras were chosen for research: VAC-135-IP with OmniVision OV9121 matrix and VAC-248-IP with OnSemiconductor VITA2000 matrix. The two tested devices were placed in a climatic chamber at the same time and illuminated by one radiation source with a color temperature about 3000 K in order to eliminate a number of methodological errors. Main Results. The temperature dependence of the signals was shown to be linear and the matrixes sensitivities were determined. The results obtained are consistent with theoretical views, in general. The coefficients of thermal sensitivity were computed by these dependencies. It is shown that the greatest affect of temperature on the sensitivity occurs in the area (0.7–1.1 mkm. Temperature coefficients of sensitivity increase with the downward radiation wavelength increase. The experiments carried out have shown that it is necessary to take into account the changes in temperature sensitivity of silicon matrixes in the red and near in IR regions of the spectrum. The effect reveals itself in a clearly negative way in cameras with an amplitude resolution of 10-12 bits used for aerospace and space spectrozonal photography. Practical Relevance

  10. Color sensitive silicon photomultiplers with micro-cell level encoding for DOI PET detectors

    Science.gov (United States)

    Shimazoe, Kenji; Koyama, Akihiro; Takahashi, Hiroyuki; Ganka, Thomas; Iskra, Peter; Marquez Seco, Alicia; Schneider, Florian; Wiest, Florian

    2017-11-01

    There have been many studies on Depth Of Interaction (DOI) identification for high resolution Positron Emission Tomography (PET) systems, including those on phoswich detectors, double-sided readout, light sharing methods, and wavelength discrimination. The wavelength discrimination method utilizes the difference in wavelength of stacked scintillators and requires a color sensitive photodetector. Here, a new silicon photomultiplier (SiPM) coupled to a color filter (colorSiPM) was designed and fabricated for DOI detection. The fabricated colorSiPM has two anode readouts that are sensitive to blue and green color. The colorSiPM's response and DOI identification capability for stacked GAGG and LYSO crystals are characterized. The fabricated colorSiPM is sensitive enough to detect a peak of 662 keV from a 137 Cs source.

  11. A highly sensitive and durable electrical sensor for liquid ethanol using thermally-oxidized mesoporous silicon

    Science.gov (United States)

    Harraz, Farid A.; Ismail, Adel A.; Al-Sayari, S. A.; Al-Hajry, A.; Al-Assiri, M. S.

    2016-12-01

    A capacitive detection of liquid ethanol using reactive, thermally oxidized films constructed from electrochemically synthesized porous silicon (PSi) is demonstrated. The sensor elements are fabricated as meso-PSi (pore sizes hydrophobic PSi surface exhibited almost a half sensitivity of the thermal oxide sensor. The response to water is achieved only at the oxidized surface and found to be ∼one quarter of the ethanol sensitivity, dependent on parameters such as vapor pressure and surface tension. The capacitance response retains ∼92% of its initial value after continuous nine cyclic runs and the sensors presumably keep long-term stability after three weeks storage, demonstrating excellent durability and storage stability. The observed behavior in current system is likely explained by the interface interaction due to dipole moment effect. The results suggest that the current sensor structure and design can be easily made to produce notably higher sensitivities for reversible detection of various analytes.

  12. Internal alignment and position resolution of the silicon tracker of DAMPE determined with orbit data

    Science.gov (United States)

    Tykhonov, A.; Ambrosi, G.; Asfandiyarov, R.; Azzarello, P.; Bernardini, P.; Bertucci, B.; Bolognini, A.; Cadoux, F.; D'Amone, A.; De Benedittis, A.; De Mitri, I.; Di Santo, M.; Dong, Y. F.; Duranti, M.; D'Urso, D.; Fan, R. R.; Fusco, P.; Gallo, V.; Gao, M.; Gargano, F.; Garrappa, S.; Gong, K.; Ionica, M.; La Marra, D.; Lei, S. J.; Li, X.; Loparco, F.; Marsella, G.; Mazziotta, M. N.; Peng, W. X.; Qiao, R.; Salinas, M. M.; Surdo, A.; Vagelli, V.; Vitillo, S.; Wang, H. Y.; Wang, J. Z.; Wang, Z. M.; Wu, D.; Wu, X.; Zhang, F.; Zhang, J. Y.; Zhao, H.; Zimmer, S.

    2018-06-01

    The DArk Matter Particle Explorer (DAMPE) is a space-borne particle detector designed to probe electrons and gamma-rays in the few GeV to 10 TeV energy range, as well as cosmic-ray proton and nuclei components between 10 GeV and 100 TeV. The silicon-tungsten tracker-converter is a crucial component of DAMPE. It allows the direction of incoming photons converting into electron-positron pairs to be estimated, and the trajectory and charge (Z) of cosmic-ray particles to be identified. It consists of 768 silicon micro-strip sensors assembled in 6 double layers with a total active area of 6.6 m2. Silicon planes are interleaved with three layers of tungsten plates, resulting in about one radiation length of material in the tracker. Internal alignment parameters of the tracker have been determined on orbit, with non-showering protons and helium nuclei. We describe the alignment procedure and present the position resolution and alignment stability measurements.

  13. High resolution, position sensitive detector for energetic particle beams

    International Nuclear Information System (INIS)

    Marsh, E.P.; Strathman, M.D.; Reed, D.A.; Odom, R.W.; Morse, D.H.; Pontau, A.E.

    1993-01-01

    The performance and design of an imaging position sensitive, particle beam detector will be presented. The detector is minimally invasive, operates a wide dynamic range (>10 10 ), and exhibits high spatial resolution. The secondary electrons produced when a particle beam passes through a thin foil are imaged using stigmatic ion optics onto a two-dimensional imaging detector. Due to the low scattering cross section of the 6 nm carbon foil the detector is a minimal perturbation on the primary beam. A prototype detector with an image resolution of approximately 5 μm for a field of view of 1 mm has been reported. A higher resolution detector for imaging small beams (<50 μm) with an image resolution of better than 0.5 μm has since been developed and its design is presented. (orig.)

  14. High resolution, position sensitive detector for energetic particle beams

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, E P [Charles Evans and Associates, Redwood City, CA (United States); Strathman, M D [Charles Evans and Associates, Redwood City, CA (United States); Reed, D A [Charles Evans and Associates, Redwood City, CA (United States); Odom, R W [Charles Evans and Associates, Redwood City, CA (United States); Morse, D H [Sandia National Labs., Livermore, CA (United States); Pontau, A E [Sandia National Labs., Livermore, CA (United States)

    1993-05-01

    The performance and design of an imaging position sensitive, particle beam detector will be presented. The detector is minimally invasive, operates a wide dynamic range (>10[sup 10]), and exhibits high spatial resolution. The secondary electrons produced when a particle beam passes through a thin foil are imaged using stigmatic ion optics onto a two-dimensional imaging detector. Due to the low scattering cross section of the 6 nm carbon foil the detector is a minimal perturbation on the primary beam. A prototype detector with an image resolution of approximately 5 [mu]m for a field of view of 1 mm has been reported. A higher resolution detector for imaging small beams (<50 [mu]m) with an image resolution of better than 0.5 [mu]m has since been developed and its design is presented. (orig.)

  15. One-dimensional position sensitive detector based on photonic crystals

    International Nuclear Information System (INIS)

    Xi Feng; Qin Lan; Xue Lian; Duan Ying

    2013-01-01

    Position sensitive detectors (PSDs) are an important class of optical sensors which utilizes the lateral photovoltaic effect (LPVE). According to the operation principle of PSD, we demonstrate that LPVE can be enhanced by lengthening the lifetime of photo-generated carriers. A PSD based on photonic crystals (PCs) composed of MgF 2 and InP is proposed and designed. The transmittances of the defect PC and the reflectance of the perfect PC in the PSD are obtained with transfer matrix method. The theoretical research on the designed device shows that LPVE is enhanced by improving the transmittance of the defect PC and the reflectance of the perfect PC to lengthen the lifetime of photo-generated carriers. (authors)

  16. Position-sensitive proportional counters using resistance-capacitance position encoding

    International Nuclear Information System (INIS)

    Kopp, M.K.; Borkowski, C.J.

    1975-12-01

    A new method was developed for encoding the position of individual photons, neutrons, or charged particles in proportional counters by using the distributed RC line characteristics of these counters. The signal processing is described and guidelines for the design and operation of these position sensitive proportional counters (PSPCs) are given. Using these guidelines, several prototypic PSPCs were constructed to improve the spatial resolution and shorten the signal processing time; for example, the intrinsic spatial uncertainty was reduced to 28 μ fwhm for alpha particles and 100 μ fwhm for low-energy x rays (2 to 6 keV). Also, the signal processing time was reduced to 0.6 μsec without seriously degrading the spatial resolution. These results have opened new fields of application of the RC position encoding method in imaging distributions of photons, charged particles, or neutrons in nuclear medicine, physics, and radiography

  17. Porosity dependence of positive magnetoconductance in n-type porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Chouaibi, Bassem; Radaoui, Moufid; Benfredj, Amel; Bouchriha, Habib [Laboratoire Materiaux Avances et Phenomenes Quantiques, Faculte des Sciences de Tunis, Universite El Manar, 2092 Campus universitaire, Tunis (Tunisia); Romdhane, Samir [Laboratoire Materiaux Avances et Phenomenes Quantiques, Faculte des Sciences de Tunis, Universite El Manar, 2092 Campus universitaire, Tunis (Tunisia); Faculte des Sciences de Bizerte, 7021 Zarzouna, Bizerte, Universite de Carthage (Tunisia); Bouaicha, Mongi [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia)

    2012-10-15

    Positive magnetoconductance (MC) on n-type porous silicon (PS) based devices was observed at room temperature for low static magnetic field (under 6000 G). We found that the measured MC decreases when the film porosity is increased. Obtained results were analyzed by means of the quasi-1D weak localization (WL) theory. From the dependence of the MC vs. applied magnetic field, we determine the phase coherence length L{sup {phi}}. Good agreement between theoretical and experimental results was found (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Beam position monitor sensitivity for low-β beams

    International Nuclear Information System (INIS)

    Shafer, R.E.

    1993-01-01

    At low velocities, the EM field of a particle in a conducting beam tube is no longer a TEM wave, but has a finite longitudinal extent. The net effect of this is to reduce the coupling of the high-frequency Fourier components of the beam current to BPM (beam position monitor) electrodes, which modifies the BPM sensitivity to beam displacement. This effect is especially pronounced for high-frequency, large-aperture pickups used for low-β beams. Non-interceptive beam position monitors used in conjunction with high frequency RFQ (radio-frequency-quadrupole) and DTL (drift-tube-linac) accelerators fall into this category. When testing a BPM with a thin wire excited with either pulses or high-frequency sinusoidal currents, the EM wave represents the principal (TEM) mode in a coaxial transmission line, which is equivalent to a highly relativistic (β = 1) beam. Thus wire measurements are not suitable for simulating slow particle beams in high bandwidth diagnostic devices that couple to the image currents in the beam tube wall. Attempts to load the tin wire either capacitively or inductively to slow the EM wave down have met with limited success. In general, the equations used to represent the 2-D response of cylindrical-geometry BPMs to charged-particle beams make several assumptions: (1) the BPM electrodes are flush with and grounded to the surface of the conducting beam tube; (2) the beam is a line source (pencil beam); (3) the longitudinal extent of the EM field of a beam particle at the beam tube wall is zero, corresponding to a highly relativistic beam. The purpose of this paper is to make some quantitative estimates of the corrections to the conventional approximations when a BPM is used to measure the position of low velocity (low-β) beams

  19. Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

    International Nuclear Information System (INIS)

    Yan, Hai; Zou, Yi; Yang, Chun-Ju; Chakravarty, Swapnajit; Wang, Zheng; Tang, Naimei; Chen, Ray T.; Fan, Donglei

    2015-01-01

    A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed

  20. Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Hai, E-mail: hai.yan@utexas.edu; Zou, Yi; Yang, Chun-Ju [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758 (United States); Chakravarty, Swapnajit, E-mail: swapnajit.chakravarty@omegaoptics.com [Omega Optics, Inc., 8500 Shoal Creek Blvd., Austin, Texas 78757 (United States); Wang, Zheng [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758 (United States); Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (United States); Tang, Naimei; Chen, Ray T., E-mail: raychen@uts.cc.utexas.edu [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758 (United States); Omega Optics, Inc., 8500 Shoal Creek Blvd., Austin, Texas 78757 (United States); Fan, Donglei [Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (United States); Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States)

    2015-03-23

    A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed.

  1. Vantage Sensitivity: Environmental Sensitivity to Positive Experiences as a Function of Genetic Differences.

    Science.gov (United States)

    Pluess, Michael

    2017-02-01

    A large number of gene-environment interaction studies provide evidence that some people are more likely to be negatively affected by adverse experiences as a function of specific genetic variants. However, such "risk" variants are surprisingly frequent in the population. Evolutionary analysis suggests that genetic variants associated with increased risk for maladaptive development under adverse environmental conditions are maintained in the population because they are also associated with advantages in response to different contextual conditions. These advantages may include (a) coexisting genetic resilience pertaining to other adverse influences, (b) a general genetic susceptibility to both low and high environmental quality, and (c) a coexisting propensity to benefit disproportionately from positive and supportive exposures, as reflected in the recent framework of vantage sensitivity. After introducing the basic properties of vantage sensitivity and highlighting conceptual similarities and differences with diathesis-stress and differential susceptibility patterns of gene-environment interaction, selected and recent empirical evidence for the notion of vantage sensitivity as a function of genetic differences is reviewed. The unique contribution that the new perspective of vantage sensitivity may make to our understanding of social inequality will be discussed after suggesting neurocognitive and molecular mechanisms hypothesized to underlie the propensity to benefit disproportionately from benevolent experiences. © 2015 Wiley Periodicals, Inc.

  2. Position sensitive regions in a generic radiation sensor based on single event upsets in dynamic RAMs

    International Nuclear Information System (INIS)

    Darambara, D.G.; Spyrou, N.M.

    1997-01-01

    Modern integrated circuits are highly complex systems and, as such, are susceptible to occasional failures. Semiconductor memory devices, particularly dynamic random access memories (dRAMs), are subject to random, transient single event upsets (SEUs) created by energetic ionizing radiation. These radiation-induced soft failures in the stored data of silicon based memory chips provide the foundation for a new, highly efficient, low cost generic radiation sensor. The susceptibility and the detection efficiency of a given dRAM device to SEUs is a complicated function of the circuit design and geometry, the operating conditions and the physics of the charge collection mechanisms involved. Typically, soft error rates measure the cumulative response of all sensitive regions of the memory by broad area chip exposure in ionizing radiation environments. However, this study shows that many regions of a dynamic memory are competing charge collection centres having different upset thresholds. The contribution to soft fails from discrete regions or individual circuit elements of the memory device is unambiguously separated. Hence the use of the dRAM as a position sensitive radiation detector, with high spatial resolution, is assessed and demonstrated. (orig.)

  3. Antimicrobial sensitivity pattern of gram positive CSF isolates in ...

    African Journals Online (AJOL)

    100%) to Linezolid, Vancomycin and Piperacillin-Tazobactam. However, Staphylococcus aureus were 100% sensitive to Linezolid and Vancomycin but were only 87.5% sensitive to Piperacillin-Tazobactam combination. The Streptococcus ...

  4. Linear position sensitive neutron detector using fiber optic encoded scintillators

    International Nuclear Information System (INIS)

    Davidson, P.L.; Wroe, H.

    1983-01-01

    A linear position sensitive slow neutron detector with 3 mm resolution is described. It uses the fiber optic coding principle in which the resolution elements are separate pieces of lithium loaded glass scintillator each coupled by means of flexible polymer optical fibers to a unique combination of 3 photo multipliers (PM's) out of a bank of 12. A decoder circuit repsponds to a triple coincidence between PM outputs and generates a 12 bit work which identifies the scintillator element which stopped the incident neutron. Some details of the construction and decoding electronics are given together with test results obtained using a laboratory isotope neutron source and a monochomated, collimated neutron beam from a reactor. The count rate in the absence of neutron sources is 2 to 3 c min - 1 per element; the element to element variation in response to a uniform flux is a few percent for 95% of the elements; the resolution as measured by a 1 mm wide prode neutron beam is 3 mm; the relative long term stability is about 0.1% over 3 days and the detection efficiency measured by comparison with an end windowed, high pressure gas counter is about 65% at a neutron wavelength of 0.9A 0

  5. The measurement of phi 60 mm x 600 mu m silicon PIN detector gamma sensitivity and time respond

    CERN Document Server

    Hu Meng Chun; Ye Wen Ying

    2002-01-01

    phi 60 mm x 600 mu m silicon PIN detector is a large area and high sensitive one which has been developed in near years. The authors have measured their gamma sensitivity and the time response. The experiment and theoretical calculated results in: sup 6 sup 0 Co gamma sensitivity is about 5 fC centre dot cm sup 2 /MeV, the rise time is about 10 ns and the half-high-width time is about 35 ns

  6. A silicon-based electrochemical sensor for highly sensitive, specific, label-free and real-time DNA detection

    International Nuclear Information System (INIS)

    Guo, Yuanyuan; Su, Shao; Wei, Xinpan; Zhong, Yiling; Su, Yuanyuan; He, Yao; Huang, Qing; Fan, Chunhai

    2013-01-01

    We herein present a new kind of silicon-based electrochemical sensor using a gold nanoparticles-decorated silicon wafer (AuNPs@Si) as a high-performance electrode, which is facilely prepared via in situ AuNPs growth on a silicon wafer. Particularly significantly, the resultant electrochemical sensor is efficacious for label-free DNA detection with high sensitivity due to the unique merits of the prepared silicon-based electrode. Typically, DNA at remarkably low concentrations (1–10 fM) could be readily detected without requiring additional signal-amplification procedures, which is better than or comparable to the lowest DNA concentration ever detected via well-studied signal-amplification-assisted electrochemical sensors. Moreover, the silicon-based sensor features high specificity, allowing unambiguous discrimination of single-based mismatches. We further show that real-time DNA assembly is readily monitored via recording the intensity changes of current signals due to the robust thermal stability of the silicon-based electrode. The unprecedented advantages of the silicon-based electrochemical sensor would offer new opportunities for myriad sensing applications. (paper)

  7. Study of Charge Diffusion in a Silicon Detector Using an Energy Sensitive Pixel Readout Chip

    CERN Document Server

    Schioppa, E. J.; van Beuzekom, M.; Visser, J.; Koffeman, E.; Heijne, E.; Engel, K. J.; Uher, J.

    2015-01-01

    A 300 μm thick thin p-on-n silicon sensor was connected to an energy sensitive pixel readout ASIC and exposed to a beam of highly energetic charged particles. By exploiting the spectral information and the fine segmentation of the detector, we were able to measure the evolution of the transverse profile of the charge carriers cloud in the sensor as a function of the drift distance from the point of generation. The result does not rely on model assumptions or electric field calculations. The data are also used to validate numerical simulations and to predict the detector spectral response to an X-ray fluorescence spectrum for applications in X-ray imaging.

  8. High sensitivity detection and characterization of the chemical state of trace element contamination on silicon wafers

    CERN Document Server

    Pianetta, Piero A; Baur, K; Brennan, S; Homma, T; Kubo, N

    2003-01-01

    Increasing the speed and complexity of semiconductor integrated circuits requires advanced processes that put extreme constraints on the level of metal contamination allowed on the surfaces of silicon wafers. Such contamination degrades the performance of the ultrathin SiO sub 2 gate dielectrics that form the heart of the individual transistors. Ultimately, reliability and yield are reduced to levels that must be improved before new processes can be put into production. It should be noted that much of this metal contamination occurs during the wet chemical etching and rinsing steps required for the manufacture of integrated circuits and industry is actively developing new processes that have already brought the metal contamination to levels beyond the measurement capabilities of conventional analytical techniques. The measurement of these extremely low contamination levels has required the use of synchrotron radiation total reflection X-ray fluorescence (SR-TXRF) where sensitivities 100 times better than conv...

  9. Sensitivity of triple-crystal X-ray diffractometers to microdefects in silicon

    International Nuclear Information System (INIS)

    Molodkin, V.B.; Olikhovskii, S.I.; Len, E.G.; Kislovskii, E.N.; Kladko, V.P.; Reshetnyk, O.V.; Vladimirova, T.P.; Sheludchenko, B.V.

    2009-01-01

    The dynamical theory, which describes both diffraction profiles and reciprocal space maps measured from imperfect crystals with account for instrumental factors of triple-crystal diffractometer (TCD), has been developed for adequate quantitative characterization of microdefects. Analytical expressions for coherent and diffuse scattering (DS) intensities measured by TCD in the Bragg diffraction geometry have been derived by using the generalized statistical dynamical theory of X-ray scattering in real single crystals with randomly distributed defects. The DS intensity distributions from single crystals containing clusters and dislocation loops have been described by explicit analytical expressions. Particularly, these expressions take into account anisotropy of displacement fields around defects with discrete orientations. Characteristics of microdefect structures in silicon single crystals grown by Czochralsky- and float-zone methods have been determined by analyzing the measured TCD profiles and reciprocal space maps. The sensitivities of reciprocal space maps and diffraction profiles to defect characteristics have been compared. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  10. Tunable detection sensitivity of opiates in urine via a label-free porous silicon competitive inhibition immunosensor.

    Science.gov (United States)

    Bonanno, Lisa M; Delouise, Lisa A

    2010-01-15

    Currently, there is need for laboratory-based high-throughput and reliable point-of-care drug screening methodologies. We demonstrate here a chip-based label-free porous silicon (PSi) photonic sensor for detecting opiates in urine. This technique provides a cost-effective alternative to conventional labeled drug screening immunoassays with potential for translation to multiplexed analysis. Important effects of surface chemistry and competitive binding assay protocol on the sensitivity of opiate detection are revealed. Capability to tune sensitivity and detection range over approximately 3 orders of magnitude (18.0 nM to 10.8 muM) was achieved by varying the applied urine specimen volume (100-5 muL), which results in systematic shifts in the competitive binding response curve. A detection range (0.36-4.02 muM) of morphine in urine (15 muL) was designed to span the current positive cutoff value (1.05 muM morphine) in medical opiate urine screening. Desirable high cross-reactivity to oxycodone, in addition to other common opiates, morphine, morphine-3-glucuronide, 6-acetyl morphine, demonstrates an advantage over current commercial screening assays, while low interference with cocaine metabolite was maintained. This study uniquely displays PSi sensor technology as an inexpensive, rapid, and reliable drug screening technology. Furthermore, the versatile surface chemistry developed can be implemented on a range of solid-supported sensors to conduct competitive inhibition assays.

  11. The Strip Silicon Photo-Multiplier: An innovation for enhanced time and position measurement

    Energy Technology Data Exchange (ETDEWEB)

    Doroud, K., E-mail: Katayoun.Doroud@cern.ch [CERN, Geneva (Switzerland); Williams, M.C.S. [CERN, Geneva (Switzerland); INFN, Bologna (Italy); Yamamoto, K. [Solid State Division, Hamamatsu Photonics K.K., Hamamatsu (Japan)

    2017-05-01

    There is considerable R&D concerning precise time measurement from a variety of detectors, and in particular for the Silicon PhotoMultiplier (SiPM). In this paper we discuss a new geometry for the SiPM in the form of a strip. A strip can be read out at both end, with each end coupled to an individual TDC (time to digital converter). The time difference is related to the position of the firing SPAD along the length of the strip, while the average of the two times gives the time of the hit. Results from the testing of the first prototype Strip SiPMs are presented in this paper.

  12. Assessing the efficiency position sensitive gaseous X-rays detectors

    International Nuclear Information System (INIS)

    Almeida, Gevaldo L. de; Souza, Maria Ines Silvani; Lopes, Ricardo T.

    2009-01-01

    Full text: The efficiency of gaseous X-ray detectors can be evaluated from tabulated data, but this approach assumes that the whole detector volume is permeated by the electrostatic field produced by the anode-cathode. Indeed, the usual detectors are comprised by a cylindrical hull acting as cathode containing a wire at its axis as anode, a configuration which foods the space between them with the electrostatic field. Some specially designed detectors, however, as Position Sensitive Detectors, contain regions which are not submitted to the electrostatic field, and hence, their efficiency could not be assessed from the tabulated data. Direct measurements of this efficiency would require a mono-chromator or set of pure mono-energetic X-rays sources. As only very few of them are really mono-energetic, the detector response to a given energy would be spoiled by to the concomitant contribution of other energies. Yet, the information would not be completely lost, but only concealed due to the convolution carried out by the detector. Therefore, a proper unfolding would be capable to recover the information, yielding the individual detector efficiency for each of the contributing energies. The degraded information is retrieved in this work through a proper mathematical unfolding of the detector response, when exposed to Bremsstrahlung spectra from an X-ray tube submitted to different voltages. For this purpose, Lorentzian functions have been fitted to these spectra - obtained with a NaI(Tl) spectrometer - in order to characterize them with proper parameters. The mathematical convolution of these functions with a theoretical detector efficiency curve yields, after integration, values which, confronted with those experimentally measured, allow the determination of the parameters of the efficiency curve. As some parameters of this curve are well known, it is possible to represent it by proper functions. For argon-filled detectors, for instance, this efficiency has a

  13. Effect of preliminary annealing of silicon substrates on the spectral sensitivity of photodetectors in bipolar integrated circuits

    International Nuclear Information System (INIS)

    Blynskij, V.I.; Bozhatkin, O.A.; Golub, E.S.; Lemeshevskaya, A.M.; Shvedov, S.V.

    2010-01-01

    We examine the results of an effect of preliminary annealing on the spectral sensitivity of photodetectors in bipolar integrated circuits, formed in silicon grown by the Czochralski method. We demonstrate the possibility of substantially improving the sensitivity of photodetectors in the infrared region of the spectrum with twostep annealing. The observed effect is explained by participation of oxidation in the gettering process, where oxidation precedes formation of a buried n + layer in the substrate. (authors)

  14. Fluorodeoxyglucose--positive internal mammary lymph node in breast cancer patients with silicone implants: is it always metastatic cancer?

    Science.gov (United States)

    Soudack, Michalle; Yelin, Alon; Simansky, David; Ben-Nun, Alon

    2013-07-01

    Patients with breast cancer following mastectomy and silicone implant reconstruction may have enlarged internal mammary lymph nodes with pathological uptake on positron emission tomography with (18)F-fluorodeoxyglucose. This lymphadenopathy is usually considered as metastatic in nature, but has also been reported to be related to other conditions, including silicon migration. The purpose of this study was to determine the rate of metastatic disease in this unique group of patients. A retrospective comparative study of 12 female patients with breast cancer with silicone implants referred for biopsy due to isolated internal mammary lymph node fluorodeoxyglucose uptake on positron emission tomography. Five patients (41.6%) had histological findings related to silicone (n = 4) or non-specific inflammation (n = 1). The remaining 7 (58.3%) had histological evidence of cancer recurrence. There was no significant difference in the fluorodeoxyglucose-standardized uptake value between the two groups. Fluorodeoxyglucose-positive mammary lymph nodes in patients with breast cancer following silicone implant reconstruction may be due to metastatic deposits, non-specific inflammation or silicone migration. Clinical and imaging characteristics are insufficient in differentiating between these conditions. Biopsy is recommended prior to initiation of further treatment.

  15. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling.

    Science.gov (United States)

    Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

    2017-01-28

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 10 3 to 10 4  s -1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'. © 2016 The Author(s).

  16. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling

    Science.gov (United States)

    Erzar, Benjamin

    2017-01-01

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 103 to 104 s−1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual–Forquin–Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’. PMID:27956504

  17. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling

    Science.gov (United States)

    Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

    2017-01-01

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 103 to 104 s-1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  18. Charge migration contribution to the sensitive layer of a silicon detector

    International Nuclear Information System (INIS)

    Croitoru, N.; Seidman, A.; Rancoita, P.G.

    1984-01-01

    The charge migration from the field-free region has been investigated, by comparing the expected peak position (which takes into account the depleted layer only) of the energy-loss of relativistic electrons with the measured one. The measurement sensitive layer was found to be systematically larger than the depleted one. This effect is accounted for the charge migration to diffusion

  19. Position, Energy, and Transit Time Distributions in a Hemispherical Deflector Analyzer with Position Sensitive Detector

    Directory of Open Access Journals (Sweden)

    Omer Sise

    2015-01-01

    Full Text Available Practical analytic equations, for the ideal field, and numerical results from SIMION simulations, for the fringing field, are presented for the exit radius rπ and transit time tπ of electrons in a hemispherical deflector analyzer (HDA over a wide range of analyzer parameters. Results are presented for a typically dimensioned HDA with mean radius R-=101.6 mm and interradial separation ΔR=R2-R1=58.4 mm able to accommodate a 40 mm diameter position sensitive detector (PSD. Results for three different entry positions R0 are compared: R0=R- (the conventional central entry and two displaced (paracentric entries: R0=82.55 mm and R0=116 mm. Exit spreads Δrπ, Δtπ and base energy resolution ΔEB are computed for HDA pass energies E0=10, 100, 500, and 1000 eV, entry aperture sizes Δr0≤1.5 mm, entry angular spreads |αmax|≤5°, and an electron beam with relative energy spread δE/E0≤0.4%. Overall, under realistic conditions, both paracentric entries demonstrate near ideal field behavior and clear superiority over the conventional entry at R0=R-. The R0=82.55 mm entry has better absolute energy and time spread resolutions, while the R0=116 mm has better relative energy resolutions, both offering attractive alternatives for time-of-flight and coincidence applications where both energy and timing resolutions are important.

  20. Ventilatory sensitivity to mild asphyxia: prone versus supine sleep position

    OpenAIRE

    Galland, B; Bolton, D; Taylor, B; Sayers, R; Williams, S

    2000-01-01

    AIMS—To compare the effects of prone and supine sleep position on the main physiological responses to mild asphyxia: increase in ventilation and arousal.
METHODS—Ventilatory and arousal responses to mild asphyxia (hypercapnia/hypoxia) were measured in 53 healthy infants at newborn and 3 months of age, during quiet sleep (QS) and active sleep (AS), and in supine and prone sleep positions. The asphyxial test mimicked face down rebreathing by slowly altering the inspired air: C...

  1. High Sensitivity and High Detection Specificity of Gold-Nanoparticle-Grafted Nanostructured Silicon Mass Spectrometry for Glucose Analysis.

    Science.gov (United States)

    Tsao, Chia-Wen; Yang, Zhi-Jie

    2015-10-14

    Desorption/ionization on silicon (DIOS) is a high-performance matrix-free mass spectrometry (MS) analysis method that involves using silicon nanostructures as a matrix for MS desorption/ionization. In this study, gold nanoparticles grafted onto a nanostructured silicon (AuNPs-nSi) surface were demonstrated as a DIOS-MS analysis approach with high sensitivity and high detection specificity for glucose detection. A glucose sample deposited on the AuNPs-nSi surface was directly catalyzed to negatively charged gluconic acid molecules on a single AuNPs-nSi chip for MS analysis. The AuNPs-nSi surface was fabricated using two electroless deposition steps and one electroless etching step. The effects of the electroless fabrication parameters on the glucose detection efficiency were evaluated. Practical application of AuNPs-nSi MS glucose analysis in urine samples was also demonstrated in this study.

  2. Graphene oxide-Ag nanoparticles-pyramidal silicon hybrid system for homogeneous, long-term stable and sensitive SERS activity

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jia [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Xu, Shicai [Shandong Provincial Key Laboratory of Biophysics, College of Physics and Electronic Information, Dezhou University, Dezhou 253023 (China); Liu, Xiaoyun; Li, Zhe; Hu, Litao; Li, Zhen; Chen, Peixi; Ma, Yong [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Jiang, Shouzhen, E-mail: jiang_sz@126.com [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Shandong Provincial Key Laboratory of Optics and Photonic Device, Jinan 250014 (China); Ning, Tingyin [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Shandong Provincial Key Laboratory of Optics and Photonic Device, Jinan 250014 (China)

    2017-02-28

    Highlights: • We directly grown AgNPs on substrate by annealing method in the quartz tube. Compare with spin-coating Ag nanoparticles solution method, we got more uniform distribution of AgNPs and the AgNPs better adsorption on the substrate. • We use a simple and lost-cost method to obtain the pyramidal silicon (PSi). The PSi possessing well-separated pyramid arrays can make contribution to the homogeneity and sensitivity of the substrate. • In our work, graphene oxide (GO) film is uniformly deposited on AgNPs and PSi by using a spin-coating method. The GO films endow the hybrid system a good stability and enhance the homogeneity and sensitivity of the substrate. - Abstract: In our work, few layers graphene oxide (GO) were directly synthesized on Ag nanoparticles (AgNPs) by spin-coating method to fabricate a GO-AgNPs hybrid structure on a pyramidal silicon (PSi) substrate for surface-enhanced Raman scattering (SERS). The GO-AgNPs-PSi substrate showed excellent Raman enhancement effect, the minimum detected concentration for Rhodamine 6G (R6G) can reach 10{sup −12} M, which is one order of magnitude lower than the AgNPs-PSi substrate and two order of magnitude lower than the GO-AgNPs-flat-Si substrate. The linear fit calibration curve with error bars is presented and the value of R{sup 2} of 612 and 773 cm{sup −1} can reach 0.986 and 0.980, respectively. The excellent linear response between the Raman intensity and R6G concentrations prove that the prepared GO-AgNPs-PSi substrates can serve as good SERS substrate for molecule detection. The maximum deviations of SERS intensities from 20 positions of the GO-AgNPs-PSi substrate are less than 8%, revealing the high homogeneity of the SERS substrate. The excellent homogeneity of the enhanced Raman signals can be attributed to well-separated pyramid arrays of PSi, the uniform morphology of AgNPs and multi-functions of GO layer. Besides, the uniform GO film can effectively protect AgNPs from oxidation and endow

  3. Analytical expression for position sensitivity of linear response beam position monitor having inter-electrode cross talk

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Mukesh, E-mail: mukeshk@rrcat.gov.in [Beam Diagnostics Section, Indus Operations, Beam Dynamics & Diagnostics Division, Raja Ramanna Centre for Advanced Technology, Indore, 452013 MP (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400 094 (India); Ojha, A.; Garg, A.D.; Puntambekar, T.A. [Beam Diagnostics Section, Indus Operations, Beam Dynamics & Diagnostics Division, Raja Ramanna Centre for Advanced Technology, Indore, 452013 MP (India); Senecha, V.K. [Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400 094 (India); Ion Source Lab., Proton Linac & Superconducting Cavities Division, Raja Ramanna Centre for Advanced Technology, Indore, 452013 MP (India)

    2017-02-01

    According to the quasi electrostatic model of linear response capacitive beam position monitor (BPM), the position sensitivity of the device depends only on the aperture of the device and it is independent of processing frequency and load impedance. In practice, however, due to the inter-electrode capacitive coupling (cross talk), the actual position sensitivity of the device decreases with increasing frequency and load impedance. We have taken into account the inter-electrode capacitance to derive and propose a new analytical expression for the position sensitivity as a function of frequency and load impedance. The sensitivity of a linear response shoe-box type BPM has been obtained through simulation using CST Studio Suite to verify and confirm the validity of the new analytical equation. Good agreement between the simulation results and the new analytical expression suggest that this method can be exploited for proper designing of BPM.

  4. Position sensitive proportional counters as focal plane detectors

    International Nuclear Information System (INIS)

    Ford, J.L.C. Jr.

    1979-01-01

    The rise time and charge division techniques for position decoding with RC-line proportional counters are reviewed. The advantages that these detectors offer as focal plane counters for nuclear spectroscopy performed with magnetic spectrographs are discussed. The theory of operation of proportional counters as position sensing devices is summarized, as well as practical aspects affecting their application. Factors limiting the position and energy resolutions obtainable with a focal plane proportional counter are evaluated and measured position and energy loss values are presented for comparison. Detector systems capable of the multiparameter measurements required for particle identification, background suppression and ray-tracing are described in order to illustrate the wide applicability of proportional counters within complex focal plane systems. Examples of the use of these counters other than with magnetic spectrographs are given in order to demonstrate their usefulness in not only nuclear physics but also in fields such as solid state physics, biology, and medicine. The influence of the new focal plane detector systems on future magnetic spectrograph designs is discussed. (Auth.)

  5. Centroid finding method for position-sensitive detectors

    International Nuclear Information System (INIS)

    Radeka, V.; Boie, R.A.

    1979-10-01

    A new centroid finding method for all detectors where the signal charge is collected or induced on strips of wires, or on subdivided resistive electrodes, is presented. The centroid of charge is determined by convolution of the sequentially switched outputs from these subdivisions or from the strips with a linear centroid finding filter. The position line width is inversely proportional to N/sup 3/2/, where N is the number of subdivisions

  6. Centroid finding method for position-sensitive detectors

    International Nuclear Information System (INIS)

    Radeka, V.; Boie, R.A.

    1980-01-01

    A new centroid finding method for all detectors where the signal charge is collected or induced on strips or wires, or on subdivided resistive electrodes, is presented. The centroid of charge is determined by convolution of the sequentially switched outputs from these subdivisions or from the strips with a linear centroid finding filter. The position line width is inversely proportional to N 3 sup(/) 2 , where N is the number of subdivisions. (orig.)

  7. A design of a valid signal selecting and position decoding ASIC for PET using silicon photomultipliers

    International Nuclear Information System (INIS)

    Cho, M.; Lim, K.-T.; Kim, J.; Lee, C.; Cho, G.; Kim, H.; Yeom, J.-Y.; Choi, H.

    2017-01-01

    In most cases, a PET system has numerous electrical components and channel circuits and thus it would rather be a bulky product. Also, most existing systems receive analog signals from detectors which make them vulnerable to signal distortions. For these reasons, channel reduction techniques are important. In this work, an ASIC for PET module is being proposed. An ASIC chip for 16 PET detector channels, VSSPDC, has been designed and simulated. The main function of the chip is 16-to-1 channel reduction, i.e., finding the position of only the valid signals, signal timing, and magnitudes in all 16 channels at every recorded event. The ASIC comprises four of 4-channel modules and a 2 nd 4-to-1 router. A single channel module comprises a transimpedance amplifier for the silicon photomultipliers, dual comparators with high and low level references, and a logic circuitry. While the high level reference was used to test the validity of the signal, the low level reference was used for the timing. The 1-channel module of the ASIC produced an energy pulse by time-over-threshold method and it also produced a time pulse with a fixed delayed time. Since the ASIC chip outputs only a few digital pulses and does not require an external clock, it has an advantage over noise properties. The cadence simulation showed the good performance of the chip as designed.

  8. Gamma ray polarimetry using a position sensitive germanium detector

    CERN Document Server

    Kroeger, R A; Kurfess, J D; Phlips, B F

    1999-01-01

    Imaging gamma-ray detectors make sensitive polarimeters in the Compton energy regime by measuring the scatter direction of gamma rays. The principle is to capitalize on the angular dependence of the Compton scattering cross section to polarized gamma rays and measure the distribution of scatter directions within the detector. This technique is effective in a double-sided germanium detector between roughly 50 keV and 1 MeV. This paper reviews device characteristics important to the optimization of a Compton polarimeter, and summarizes measurements we have made using a device with a 5x5 cm active area, 1 cm thickness, and strip-electrodes on a 2 mm pitch.

  9. Plastic scintillators utilization in position sensitive detection systems

    International Nuclear Information System (INIS)

    Garcia, Marcelo Bernardes; Soares, Adalberto Jose; Baptista Filho, Benedito Dias

    2002-01-01

    This paper shows the viability of using a plastic scintillator detector to determine the one dimension position of a radioactive source. The experiments were performed using collimated 99m Tc sources of several activities supplied by the Centro de Radiofarmacia (from IPEN), and a 15 cm long plastic scintillator with diameter 5,08 cm, produced by the Centro de Tecnologia das Radiacoes (also from IPEN). The spectrum was obtained using the Genie 2000 software, and the results processed using a neural network specially developed for the proposed application. The final results demonstrate the viability of the proposed application. (author)

  10. Cellular automaton-based position sensitive detector equalization

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-06-01

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

  11. Three-dimensional, position-sensitive radiation detection

    Science.gov (United States)

    He, Zhong; Zhang, Feng

    2010-04-06

    Disclosed herein is a method of determining a characteristic of radiation detected by a radiation detector via a multiple-pixel event having a plurality of radiation interactions. The method includes determining a cathode-to-anode signal ratio for a selected interaction of the plurality of radiation interactions based on electron drift time data for the selected interaction, and determining the radiation characteristic for the multiple-pixel event based on both the cathode-to-anode signal ratio and the electron drift time data. In some embodiments, the method further includes determining a correction factor for the radiation characteristic based on an interaction depth of the plurality of radiation interactions, a lateral distance between the selected interaction and a further interaction of the plurality of radiation interactions, and the lateral positioning of the plurality of radiation interactions.

  12. 1-D position sensitive single carrier semiconductor detectors

    International Nuclear Information System (INIS)

    Zhong He; Knoll, G.F.; Wehe, D.K.; Rojeski, R.; Mastrangelo, C.H.; Hammig, M.; Barrett, C.; Uritani, A.

    1996-01-01

    A single polarity charge sensing method has been studied using coplanar electrodes on 5 mm cubes of CdZnTe γ-ray detectors. This method can ameliorate the hole trapping problem of room-temperature semiconductor detectors. Our experimental results confirm that the energy resolution is dramatically improved compared with that obtained using the conventional readout method, but is still about an order of magnitude worse than the theoretical limit. A method to obtain the γ-ray interaction depth between the cathode and the anode is presented here. This technique could be used to correct for the electron trapping as a function of distance from the coplanar electrodes. Experimental results showed that a position resolution of about 0.9 mm FWHM at 122 keV can be obtained. These results will be of interest in the design of higher performance room-temperature semiconductor γ-ray detectors. (orig.)

  13. Cellular automaton-based position sensitive detector equalization

    International Nuclear Information System (INIS)

    Ferrando, Nestor; Herrero, V.; Cerda, J.; Lerche, C.W.; Colom, R.J.; Gadea, R.; Martinez, J.D.; Monzo, J.M.; Mateo, F.; Sebastia, A.; Benlloch, J.M.

    2009-01-01

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

  14. Design Approaches for Enhancing Photovoltaic Performance of Silicon Solar Cells Sensitized by Proximal Nanocrystalline Quantum Dots

    Science.gov (United States)

    Shafiq, Natis

    Energy transfer (ET) based sensitization of silicon (Si) using proximal nanocrystal quantum dots (NQDs) has been studied extensively in recent years as a means to develop thin and flexible Si based solar cells. The driving force for this research activity is a reduction in materials cost. To date, the main method for determining the role of ET in sensitizing Si has been optical spectroscopic studies. The quantitative contribution from two modes of ET (namely, nonradiative and radiative) has been reported using time-resolved photoluminescence (TRPL) spectroscopy coupled with extensive theoretical modelling. Thus, optical techniques have established the potential for utilizing ET based sensitization of Si as a feasible way to develop novel NQD-Si hybrid solar cells. However, the ultimate measure of the efficiency of ET-based mechanisms is the generation of electron-hole pairs by the impinging photons. It is therefore important to perform electrical measurements. However, only a couple of studies have attempted electrical quantification of ET modes. A few studies have focused on photocurrent measurements, without considering industrially relevant photovoltaic (PV) systems. Therefore, there is a need to develop a systematic approach for the electrical quantification of ET-generated charges and to help engineer new PV architectures optimized for harnessing the full advantages of ET mechanisms. Within this context, the work presented in this dissertation aims to develop an experimental testing protocol that can be applied to different PV structures for quantifying ET contributions from electrical measurements. We fabricated bulk Si solar cells (SCs) as a test structure and utilized CdSe/ZnS NQDs for ET based sensitization. The NQD-bulk Si hybrid devices showed ˜30% PV enhancement after NQD deposition. We measured external quantum efficiency (EQE) of these devices to quantify ET-generated charges. Reflectance measurements were also performed to decouple contributions of

  15. High Sensitivity Detection of CdSe/ZnS Quantum Dot-Labeled DNA Based on N-type Porous Silicon Microcavities.

    Science.gov (United States)

    Lv, Changwu; Jia, Zhenhong; Lv, Jie; Zhang, Hongyan; Li, Yanyu

    2017-01-01

    N-type macroporous silicon microcavity structures were prepared using electrochemical etching in an HF solution in the absence of light and oxidants. The CdSe/ZnS water-soluble quantum dot-labeled DNA target molecules were detected by monitoring the microcavity reflectance spectrum, which was characterized by the reflectance spectrum defect state position shift resulting from changes to the structures' refractive index. Quantum dots with a high refractive index and DNA coupling can improve the detection sensitivity by amplifying the optical response signals of the target DNA. The experimental results show that DNA combined with a quantum dot can improve the sensitivity of DNA detection by more than five times.

  16. Development of Position-Sensitive Magnetic Calorimeters for X-Ray Astronomy

    Science.gov (United States)

    Bandler, SImon; Stevenson, Thomas; Hsieh, Wen-Ting

    2011-01-01

    pixilated array of x-ray absorbers shares fewer numbers of temperature sensors. A means of discriminating the signals from different absorber positions, however, needs to be built into the device for each sensor. The design concept for the device is such that the shape of the temperature pulse with time depends on the location of the absorber. This inherent position sensitivity of the signal is then analyzed to determine the location of the event precisely, effectively yielding one device with many sub-pixels. With such devices, the total number of electronic channels required to read out a given number of pixels is significantly reduced. PoSMs were developed that consist of four discrete absorbers connected to a single magnetic sensor. The design concept can be extended to more than four absorbers per sensor. The thermal conductance between the sensor and each absorber is different by design and consequently, the pulse shapes are different depending upon which absorber the xrays are received, allowing position discrimination. A magnetic sensor was used in which a paramagnetic Au:Er temperature-sensitive material is located in a weak magnetic field. Deposition of energy from an x-ray photon causes an increase in temperature, which leads to a change of magnetization of the paramagnetic sensor, which is subsequently read out using a low noise dc-SQUID. The PoSM microcalorimeters are fully microfabricated: the Au:Er sensor is located above the meander, with a thin insulation gap in between. For this position-sensitive device, four electroplated absorbers are thermally linked to the sensor via heat links of different thermal conductance. One pixel is identical to that of a single-pixel design, consisting of an overhanging absorber fabricated directly on top of the sensor. It is therefore very strongly thermally coupled to it. The three other absorbers are supported directly on a silicon-nitride membrane. These absorbers are thermally coupled to the sensor via Ti (5 nm)/Au250 nm

  17. Flat Panel PMT: advances in position sensitive photodetection

    International Nuclear Information System (INIS)

    Pani, R.; Pellegrini, R.; Trotta, C.; Cinti, M.N.; Bennati, P.; Trotta, G.; Iurlaro, G.; Montani, L.; Ridolfi, S.; Cusanno, F.; Garibaldi, F.

    2003-01-01

    Over the last ten years there was being a strong advancement in photodetection. Different application fields are involved in their use in particular high energy physics, astrophysics and nuclear medicine. They usually work by coupling a scintillation crystal and more recent scintillation arrays with pixel size as small as 0.5 mm. PSPMT represents today the most ready technology for photodetection with large detection areas and very high spatial resolution. Flat panel PMT represents the last technological advancement. Its dimension is 50x50 mm 2 with a narrow peripheral dead zone (0.5 mm final goal). Its compactness allow to assemble different modules closely packed, achieving large detection areas with an effective active area of 97%. In this paper we analyze the imaging performances of PSPMT by coupling two scintillation arrays and by light spot scanning of photocathode to evaluate the linearity position response, spatial resolution and uniformity gain response as a function of light distribution spread and the number of photoelectrons generated on photocathode. The results point out a very narrow PMT intrinsic charge spread and low cross-talk between anodes. Energy resolution and spatial resolution show a good linearity with DRF variation. An unexpected intra-anode gain variation is carried out. In this paper we present the results obtained with this PSPMT regarding imaging performances principally addressed to nuclear medicine application

  18. Evaluation of the x-ray response of a position-sensitive microstrip detector with an integrated readout chip

    International Nuclear Information System (INIS)

    Rossington, C.; Jaklevic, J.; Haber, C.; Spieler, H.; Reid, J.

    1990-08-01

    The performance of an SVX silicon microstrip detector and its compatible integrated readout chip have been evaluated in response to Rh Kα x-rays (average energy 20.5 keV). The energy and spatial discrimination capabilities, efficient data management and fast readout rates make it an attractive alternative to the CCD and PDA detectors now being offered for x-ray position sensitive diffraction and EXAFS work. The SVX system was designed for high energy physics applications and thus further development of the existing system is required to optimize it for use in practical x-ray experiments. For optimum energy resolution the system noise must be decreased to its previously demonstrated low levels of 2 keV FWHM at 60 keV or less, and the data handling rate of the computer must be increased. New readout chips are now available that offer the potential of better performance. 15 refs., 7 figs

  19. Angular sensitivity of modeled scientific silicon charge-coupled devices to initial electron direction

    Energy Technology Data Exchange (ETDEWEB)

    Plimley, Brian, E-mail: brian.plimley@gmail.com [Nuclear Engineering Department, University of California, Berkeley, CA (United States); Coffer, Amy; Zhang, Yigong [Nuclear Engineering Department, University of California, Berkeley, CA (United States); Vetter, Kai [Nuclear Engineering Department, University of California, Berkeley, CA (United States); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2016-08-11

    Previously, scientific silicon charge-coupled devices (CCDs) with 10.5-μm pixel pitch and a thick (650 μm), fully depleted bulk have been used to measure gamma-ray-induced fast electrons and demonstrate electron track Compton imaging. A model of the response of this CCD was also developed and benchmarked to experiment using Monte Carlo electron tracks. We now examine the trade-off in pixel pitch and electronic noise. We extend our CCD response model to different pixel pitch and readout noise per pixel, including pixel pitch of 2.5 μm, 5 μm, 10.5 μm, 20 μm, and 40 μm, and readout noise from 0 eV/pixel to 2 keV/pixel for 10.5 μm pixel pitch. The CCD images generated by this model using simulated electron tracks are processed by our trajectory reconstruction algorithm. The performance of the reconstruction algorithm defines the expected angular sensitivity as a function of electron energy, CCD pixel pitch, and readout noise per pixel. Results show that our existing pixel pitch of 10.5 μm is near optimal for our approach, because smaller pixels add little new information but are subject to greater statistical noise. In addition, we measured the readout noise per pixel for two different device temperatures in order to estimate the effect of temperature on the reconstruction algorithm performance, although the readout is not optimized for higher temperatures. The noise in our device at 240 K increases the FWHM of angular measurement error by no more than a factor of 2, from 26° to 49° FWHM for electrons between 425 keV and 480 keV. Therefore, a CCD could be used for electron-track-based imaging in a Peltier-cooled device.

  20. Highly sensitive and selective detection of dopamine using one-pot synthesized highly photoluminescent silicon nanoparticles.

    Science.gov (United States)

    Zhang, Xiaodong; Chen, Xiaokai; Kai, Siqi; Wang, Hong-Yin; Yang, Jingjing; Wu, Fu-Gen; Chen, Zhan

    2015-03-17

    A simple and highly efficient method for dopamine (DA) detection using water-soluble silicon nanoparticles (SiNPs) was reported. The SiNPs with a high quantum yield of 23.6% were synthesized by using a one-pot microwave-assisted method. The fluorescence quenching capability of a variety of molecules on the synthesized SiNPs has been tested; only DA molecules were found to be able to quench the fluorescence of these SiNPs effectively. Therefore, such a quenching effect can be used to selectively detect DA. All other molecules tested have little interference with the dopamine detection, including ascorbic acid, which commonly exists in cells and can possibly affect the dopamine detection. The ratio of the fluorescence intensity difference between the quenched and unquenched cases versus the fluorescence intensity without quenching (ΔI/I) was observed to be linearly proportional to the DA analyte concentration in the range from 0.005 to 10.0 μM, with a detection limit of 0.3 nM (S/N = 3). To the best of our knowledge, this is the lowest limit for DA detection reported so far. The mechanism of fluorescence quenching is attributed to the energy transfer from the SiNPs to the oxidized dopamine molecules through Förster resonance energy transfer. The reported method of SiNP synthesis is very simple and cheap, making the above sensitive and selective DA detection approach using SiNPs practical for many applications.

  1. A two-dimensional low energy gamma-ray position sensitive detector

    International Nuclear Information System (INIS)

    Charalambous, P.M.; Dean, A.J.; Drane, M.; Gil, A.; Stephen, J.B.; Young, N.G.S.; Barbareschi, L.; Perotti, F.; Villa, G.; Badiali, M.; La Padula, C.; Polcaro, F.; Ubertini, P.

    1984-01-01

    An array of 1-dimensional position sensitive detectors designed to operate over the photon energy range 0.2-10.0 MeV, so as to form an efficient 2-dimensional position sensitive detection plane is described. A series of experimental tests has been carried out to evaluate and confirm the computed capabilities. (orig.)

  2. A position-sensitive scintillation detector for two-dimensional angular correlation of annihilation radiation using metal-package position-sensitive photomultiplier tubes

    International Nuclear Information System (INIS)

    Inoue, Koji; Nagai, Yasuyoshi; Saito, Haruo; Nagashima, Yasuyuki; Hyodo, Toshio; Muramatsu, Shinichi; Nagai, Shota

    1999-01-01

    We have constructed and tested a prototype of a new position sensitive γ-ray detector which consists of an array of 2.6x2.6x18 mm 3 BGO scintillator blocks, a light guide, and four metal-package position-sensitive photomultiplier tubes (R5900-00-C8) recently developed by Hamamatsu Photonics Co. Ltd. Scalability of the detector of this type makes it possible to construct a larger detector using many PS-PMTs, which will be useful for the two-dimensional angular correlation of annihilation radiation apparatus

  3. Passive Removal of Silicone Oil with Temporal Head Position through Two 23-Gauge Cannulas

    Directory of Open Access Journals (Sweden)

    Zhong Lin

    2016-01-01

    Full Text Available Purpose. To report a new approach for removal of silicone oil. Methods. All surgeries were performed using 23-gauge vitrectomy system with two transconjunctival sutureless cannulas. At the beginning, most of the silicone oil was removed by traditional microinvasive vitrectomy system through inferior-temporal cannula. Then, the blood transfusion tube is removed from the inferior-temporal cannula, and the fluid-air exchange is performed. A passive fluid-air exchange was performed to aspirate the residual silicone oil after gradually turning the patient’s head temporally by approximately 90° gradually. Results. After the surgery, all patients had a clear anterior chamber and vitreous cavity on slit lamp and B scan examination, respectively. The mean time taken for silicone oil removal and total surgery was 8.0±1.4 minutes and 12.4±2.5 minutes, respectively. The mean intraocular pressure 1 day, 3 days, 1 week, 1 month, and 3 months after surgery was 9.0±5.8 mmHg, 11.3±7.6 mmHg, 16.1±6.9 mmHg, 17.7±4.8 mmHg, and 17.1±3.5 mmHg, respectively. Conclusion. This new approach may provide a safe and fast method to remove the silicone oil.

  4. Use of Opioid Medications for Employees in Critical Safety or Security Positions and Positions with Safety Sensitive Duties

    Science.gov (United States)

    2017-01-30

    can cause harm) to the physical well-being of or jeopardize the security of the employee , co-workers, customers or the general public through a lapse...DEPARTMENT OF THE ARMY US ARMY PUBLIC HEALTH CENTER 5158 BLACKHAWK ROAD ABERDEEN PROVING GROUND MARYLAND 21010-5403 Directorate of Clinical... Employees in Critical Safety or Security Positions and Positions with Safety Sensitive Duties. 1. REFERENCES. A. Army Regulation 40-5, Preventive

  5. Tuning Light Emission of a Pressure-Sensitive Silicon/ZnO Nanowires Heterostructure Matrix through Piezo-phototronic Effects.

    Science.gov (United States)

    Chen, Mengxiao; Pan, Caofeng; Zhang, Taiping; Li, Xiaoyi; Liang, Renrong; Wang, Zhong Lin

    2016-06-28

    Based on white light emission at silicon (Si)/ZnO hetrerojunction, a pressure-sensitive Si/ZnO nanowires heterostructure matrix light emitting diode (LED) array is developed. The light emission intensity of a single heterostructure LED is tuned by external strain: when the applied stress keeps increasing, the emission intensity first increases and then decreases with a maximum value at a compressive strain of 0.15-0.2%. This result is attributed to the piezo-phototronic effect, which can efficiently modulate the LED emission intensity by utilizing the strain-induced piezo-polarization charges. It could tune the energy band diagrams at the junction area and regulate the optoelectronic processes such as charge carriers generation, separation, recombination, and transport. This study achieves tuning silicon based devices through piezo-phototronic effect.

  6. Prototype of high resolution PET using resistive electrode position sensitive CdTe detectors

    International Nuclear Information System (INIS)

    Kikuchi, Yohei; Ishii, Keizo; Matsuyama, Shigeo; Yamazaki, Hiromichi

    2008-01-01

    Downsizing detector elements makes it possible that spatial resolutions of positron emission tomography (PET) cameras are improved very much. From this point of view, semiconductor detectors are preferable. To obtain high resolution, the pixel type or the multi strip type of semiconductor detectors can be used. However, in this case, there is a low packing ratio problem, because a dead area between detector arrays cannot be neglected. Here, we propose the use of position sensitive semiconductor detectors with resistive electrode. The CdTe detector is promising as a detector for PET camera because of its high sensitivity. In this paper, we report development of prototype of high resolution PET using resistive electrode position sensitive CdTe detectors. We made 1-dimensional position sensitive CdTe detectors experimentally by changing the electrode thickness. We obtained 750 A as an appropriate thickness of position sensitive detectors, and evaluated the performance of the detector using a collimated 241 Am source. A good position resolution of 1.2 mm full width half maximum (FWHM) was obtained. On the basis of the fundamental development of resistive electrode position sensitive detectors, we constructed a prototype of high resolution PET which was a dual head type and was consisted of thirty-two 1-dimensional position sensitive detectors. In conclusion, we obtained high resolutions which are 0.75 mm (FWHM) in transaxial, and 1.5 mm (FWHM) in axial. (author)

  7. A position-sensitive start detector for time-of-flight measurement

    International Nuclear Information System (INIS)

    Ikezoe, Hiroshi; Shikazono, Naomoto; Isoyama, Goro.

    1978-08-01

    A position-sensitive start detector for a time-of-flight measurement is described. In this detector microchannel plates were used to obtain time and position signals simultaneously. A time resolution of 121 psec FWHM and a position resolution of 0.28 mm FWHM were obtained for α-particles from an 241 Am source. (auth.)

  8. Signal collection and position reconstruction of silicon strip detectors with 200 μm readout pitch

    International Nuclear Information System (INIS)

    Krammer, M.; Pernegger, H.

    1997-01-01

    Silicon strip detectors with large readout pitch and intermediate strips offer an interesting approach to reduce the number of readout channels in the tracking systems of future collider experiments without compromising too much on the spatial resolution. Various detector geometries with a readout pitch of 200 μm have been studied for their signal response and spatial resolution. (orig.)

  9. The measurement of the radioactive aerosol diameter by position sensitive detectors, 3

    International Nuclear Information System (INIS)

    Murakami, Hiroyuki; Nakamoto, Atsushi; Kanamori, Masashi; Seki, Akio.

    1981-10-01

    The measurement of the diameter of radioactive aerosol, in particular plutonium aerosol, is very important for the internal dose estimation. Determination of the diameter of radioactive aerosol is performed by using the position sensitive detectors. Position sensitive semiconductor detectors and Scintillation detectors with IIT tube are used as the position sensitive detector. The filter paper with the radioactive aerosols is contacted to the PSD which is connected to the data processor so that the diameter of the aerosol is calculated from the measured radioactivity. (author)

  10. An X-ray gas position sensitive detector: construction and characterization

    International Nuclear Information System (INIS)

    Barbosa, A.F.; Gabriel, A.; Gabriel, A.; Craievich, A.

    1988-01-01

    A linear x-ray gas position sensitive detector with delay line readout has been constructed. The detector is described, characterized and used for detecting x-ray diffraction patterns from polycrystals. (author) [pt

  11. Enhancing the far-ultraviolet sensitivity of silicon complementary metal oxide semiconductor imaging arrays

    Science.gov (United States)

    Retherford, Kurt D.; Bai, Yibin; Ryu, Kevin K.; Gregory, James A.; Welander, Paul B.; Davis, Michael W.; Greathouse, Thomas K.; Winters, Gregory S.; Suntharalingam, Vyshnavi; Beletic, James W.

    2015-10-01

    We report our progress toward optimizing backside-illuminated silicon P-type intrinsic N-type complementary metal oxide semiconductor devices developed by Teledyne Imaging Sensors (TIS) for far-ultraviolet (UV) planetary science applications. This project was motivated by initial measurements at Southwest Research Institute of the far-UV responsivity of backside-illuminated silicon PIN photodiode test structures, which revealed a promising QE in the 100 to 200 nm range. Our effort to advance the capabilities of thinned silicon wafers capitalizes on recent innovations in molecular beam epitaxy (MBE) doping processes. Key achievements to date include the following: (1) representative silicon test wafers were fabricated by TIS, and set up for MBE processing at MIT Lincoln Laboratory; (2) preliminary far-UV detector QE simulation runs were completed to aid MBE layer design; (3) detector fabrication was completed through the pre-MBE step; and (4) initial testing of the MBE doping process was performed on monitoring wafers, with detailed quality assessments.

  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. Investigation of positive roles of hydrogen plasma treatment for interface passivation based on silicon heterojunction solar cells

    International Nuclear Information System (INIS)

    Zhang, Liping; Liu, Wenzhu; Liu, Jinning; Shi, Jianhua; Meng, Fanying; Liu, Zhengxin; Guo, Wanwu; Bao, Jian

    2016-01-01

    The positive roles of H 2 -plasma treatment (HPT) have been investigated by using different treatment procedures in view of the distinctly improved passivation performance of amorphous-crystalline silicon heterojunctions (SHJs). It has been found that a hydrogenated amorphous silicon thin film and crystalline silicon (a-Si:H/c-Si) interface with a high stretching mode (HSM) is detrimental to passivation. A moderate pre-HPT introduces atomic H, which plays an effective tuning role in decreasing the interfacial HSM; unfortunately, an epitaxial layer is formed. Further improvement in passivation can be achieved in terms of increasing the HSM of a-Si:H film treated by appropriate post-HPT based on the a-Si:H thickness. The minority carrier lifetime of crystalline wafers can be improved by treated films containing a certain quantity of crystallites. The microstructure factor R and the maximum intensity of the dielectric function ε 2max have been found to be critical microstructure parameters that describe high-quality a-Si:H passivation layers, which are associated with the amorphous-to-microcrystalline transition phase induced by multi-step HPT. Finally, the open circuit voltage and conversion efficiency of the SHJ solar cell can be improved by implementing an effective HPT process. (paper)

  14. Hybrid organic/inorganic position-sensitive detectors based on PEDOT:PSS/n-Si

    Science.gov (United States)

    Javadi, Mohammad; Gholami, Mahdiyeh; Torbatiyan, Hadis; Abdi, Yaser

    2018-03-01

    Various configurations like p-n junctions, metal-semiconductor Schottky barriers, and metal-oxide-semiconductor structures have been widely used in position-sensitive detectors. In this report, we propose a PEDOT:PSS/n-Si heterojunction as a hybrid organic/inorganic configuration for position-sensitive detectors. The influence of the thickness of the PEDOT:PSS layer, the wavelength of incident light, and the intensity of illumination on the device performance are investigated. The hybrid PSD exhibits very high sensitivity (>100 mV/mm), excellent nonlinearity (0.995) with a response time of heterojunction are very promising for developing a new class of position-sensitive detectors based on the hybrid organic/inorganic junctions.

  15. A digital divider with extension bits for position-sensitive detectors

    International Nuclear Information System (INIS)

    Koike, Masaki; Hasegawa, Ken-ichi

    1988-01-01

    Digitizing errors produced in a digital divider for position-sensitive detectors have been reduced by adding extension bits to data bits. A relation between the extension bits and the data bits to obtain perfect position uniformity is also given. A digital divider employing 10 bit ADCs and 6 bit extension circuits has been constructed. (orig.)

  16. Sensitization of erbium in silicon-rich silica : the effect of annealing temperature and hydrogen passivation

    International Nuclear Information System (INIS)

    Wilkinson, A.R.; Forcales, M.; Elliman, R.G.

    2005-01-01

    This paper reports on the effect of annealing temperature and hydrogen passivation on the excitation cross-section and photoluminescence of erbium in silicon-rich silica. Samples were prepared by co-implantation of Si and Er into SiO 2 followed by a single thermal anneal at temperatures ranging from 800 to 1100 degrees C, and with or without hydrogen passivation performed at 500 degrees C. Using time-resolved photoluminescence, the effective erbium excitation cross-section is shown to increase by a factor 3, while the number of optically active erbium ions decreases by a factor of 4 with increasing annealing temperature. Hydrogen passivation is shown to increase the luminescence intensity and to shorten the luminescence lifetime at 1.54 μm only in the presence of Si nanocrystals. The implications fo these results for realizing a silicon-based optical amplifier are also discussed. (author). 19 refs., 3 figs

  17. Ultra-sensitive and selective detection of mercury ion (Hg2+) using free-standing silicon nanowire sensors

    Science.gov (United States)

    Jin, Yan; Gao, Anran; Jin, Qinghui; Li, Tie; Wang, Yuelin; Zhao, Jianlong

    2018-04-01

    In this paper, ultra-sensitive and highly selective Hg2+ detection in aqueous solutions was studied by free-standing silicon nanowire (SiNW) sensors. The all-around surface of SiNW arrays was functionalized with (3-Mercaptopropyl)trimethoxysilane serving as Hg2+ sensitive layer. Due to effective electrostatic control provided by the free-standing structure, a detection limit as low as 1 ppt was obtained. A linear relationship (R 2 = 0.9838) between log(CHg2+ ) and a device current change from 1 ppt to 5 ppm was observed. Furthermore, the developed SiNW sensor exhibited great selectivity for Hg2+ over other heavy metal ions, including Cd2+. Given the extraordinary ability for real-time Hg2+ detection, the small size and low cost of the SiNW device, it is expected to be a potential candidate in field detection of environmentally toxic mercury.

  18. Cascaded nano-porous silicon for high sensitive biosensing and functional group distinguishing by Mid-IR spectra.

    Science.gov (United States)

    Nguyen, Minh-Hang; Tsai, Hau-Jie; Wu, Jen-Kuei; Wu, Yi-Shiuan; Lee, Ming-Chang; Tseng, Fan-Gang

    2013-09-15

    We present a chemical-biosensor in the Mid-IR range and based on cascaded porous silicon made on p- and n-type (100) silicon substrates of resistivities between 0.001Ωcm and 0.005Ωcm. The stacked porous layers of various porosities (20-80%) and thicknesses (5-9μm) are formed by successive electrochemical etchings with different current densities. Working with FTIR technique that possesses fast response, high sensitivity, and capability of detecting and identifying functional groups, the cascaded porous structures provided enhanced refractive index sensitivities and reduced detection limits in chemical and biodetection. The largest wavenumber shifts were 50cm(-1)/mM obtained for d-(+)-glucose and 96cm(-1)/μg/mL for Cy5-conjungated Rabbit Anti-Mouse IgG. The lowest detectable concentration of glucose was 80μM (1.4mg/mL) with PS porosity of 40% and thickness of about 9μm while it was 40ng/mL for Cy5-conjugated Rabbit Anti-Mouse IgG which is 2.5×10(5) folds better than those in literature. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Maternal sensitivity and latency to positive emotion following challenge: pathways through effortful control.

    Science.gov (United States)

    Conway, Anne; McDonough, Susan C; Mackenzie, Michael; Miller, Alison; Dayton, Carolyn; Rosenblum, Katherine; Muzik, Maria; Sameroff, Arnold

    2014-01-01

    The ability to self-generate positive emotions is an important component of emotion regulation. In this study, we focus on children's latency to express positive emotions following challenging situations and assess whether this ability operates through early maternal sensitivity and children's effortful control. Longitudinal relations between maternal sensitivity, infant negative affect, effortful control, and latency to positive emotion following challenge were examined in 156 children who were 33 months of age. Structural equation models supported the hypothesis that maternal sensitivity during infancy predicted better effortful control and, in turn, shorter latencies to positive emotions following challenge at 33 months. Directions for future research are discussed. © 2014 Michigan Association for Infant Mental Health.

  20. Sensitive silicon PIN-diode dosimeter for fast neutrons and method to control and increase its sensitivity

    International Nuclear Information System (INIS)

    Swinehart, P.R.; Swartz, J.M.

    1978-01-01

    With the personnel dosimeter, applicable e.g. in medicine, a dose of 0.1 rad for neutrons with an energy greater than 10 keV can be detected. In the range between 0.1 and 20 rad sensitivity is increased to 5 mV/rad. This sensitivity can be achieved by distributing the mass of the semiconductor material of the diode or equal to four times the reciprocal base width. Appropriate dimensions are 750 μm for the edge length of the end surface resp. diameter and 750 μm up to 5000 μm for the base width. (DG) [de

  1. Position sensitive photon detectors for nuclear physics, particle physics and healthcare applications

    International Nuclear Information System (INIS)

    Seitz, B

    2012-01-01

    Modern experiments in hadronic physics require detector systems capable of identifying and reconstructing all final-state particles and their momentum vectors. Imaging Cherenkov counters (RICH and DIRC) are frequently employed in nuclear and particle physics experiments. These detectors require high-rate, single-photon capable light detection system with sufficient granularity and position resolution. Several candidate systems are available, ranging from multi-anode photomultiplier tubes to micro-channel plate systems to silicon photomultipliers. Each of these detection solutions has particular advantages and disadvantages. Detailed studies of rate dependence, cross-talk, time-resolution and position resolution for a range of available photon detection solutions are presented. These properties make these photon detection systems ideal for radionuclide imaging applications. Cherenkov radiation can also be used for medical imaging applications. Two different applications using the Cherenkov effect for radionuclide imaging will be reviewed.

  2. Nanowire size dependence on sensitivity of silicon nanowire field-effect transistor-based pH sensor

    Science.gov (United States)

    Lee, Ryoongbin; Kwon, Dae Woong; Kim, Sihyun; Kim, Sangwan; Mo, Hyun-Sun; Kim, Dae Hwan; Park, Byung-Gook

    2017-12-01

    In this study, we investigated the effects of nanowire size on the current sensitivity of silicon nanowire (SiNW) ion-sensitive field-effect transistors (ISFETs). The changes in on-current (I on) and resistance according to pH were measured in fabricated SiNW ISFETs of various lengths and widths. As a result, it was revealed that the sensitivity expressed as relative I on change improves as the width decreases. Through technology computer-aided design (TCAD) simulation analysis, the width dependence on the relative I on change can be explained by the observation that the target molecules located at the edge region along the channel width have a stronger effect on the sensitivity as the SiNW width is reduced. Additionally, the length dependence on the sensitivity can be understood in terms of the resistance ratio of the fixed parasitic resistance, including source/drain resistance, to the varying channel resistance as a function of channel length.

  3. Sensitive detection of copper ions via ion-responsive fluorescence quenching of engineered porous silicon nanoparticles

    Science.gov (United States)

    Hwang, Jangsun; Hwang, Mintai P.; Choi, Moonhyun; Seo, Youngmin; Jo, Yeonho; Son, Jaewoo; Hong, Jinkee; Choi, Jonghoon

    2016-10-01

    Heavy metal pollution has been a problem since the advent of modern transportation, which despite efforts to curb emissions, continues to play a critical role in environmental pollution. Copper ions (Cu2+), in particular, are one of the more prevalent metals that have widespread detrimental ramifications. From this perspective, a simple and inexpensive method of detecting Cu2+ at the micromolar level would be highly desirable. In this study, we use porous silicon nanoparticles (NPs), obtained via anodic etching of Si wafers, as a basis for undecylenic acid (UDA)- or acrylic acid (AA)-mediated hydrosilylation. The resulting alkyl-terminated porous silicon nanoparticles (APS NPs) have enhanced fluorescence stability and intensity, and importantly, exhibit [Cu2+]-dependent quenching of fluorescence. After determining various aqueous sensing conditions for Cu2+, we demonstrate the use of APS NPs in two separate applications - a standard well-based paper kit and a portable layer-by-layer stick kit. Collectively, we demonstrate the potential of APS NPs in sensors for the effective detection of Cu2+.

  4. Position-Sensitive Detector with Depth-of-Interaction Determination for Small Animal PET

    CERN Document Server

    Fedorov, A; Kholmetsky, A L; Korzhik, M V; Lecoq, P; Lobko, A S; Missevitch, O V; Tkatchev, A

    2002-01-01

    Crystal arrays made of LSO and LuAP crystals 2x2x10 mm pixels were manufactured for evaluation of detector with depth-of-interaction (DOI) determination capability intended for small animal positron emission tomograph. Position-sensitive LSO/LuAP phoswich DOI detector based on crystal 8x8 arrays and HAMAMATSU R5900-00-M64 position-sensitive multi-anode photomultiplier tube was developed and evaluated. Time resolution was found to be not worse than 1.0 ns FWHM for both layers, and spatial resolution mean value was 1.5 mm FWHM for the center of field-of-view.

  5. Development of 2D-ACAR apparatus using position-sensitive photomultiplier tubes

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, Yasuyoshi; Saito, Haruo; Iwata, Tetsuya; Nagashima, Yasuyuki; Hyodo, Toshio [Tokyo Univ. (Japan). Coll. of Arts and Sciences; Uchida, Hiroshi; Omura, Tomohide

    1997-03-01

    A new two-dimensional angular correlation of annihilation radiation apparatus is described. Position-sensitive photomultiplier tubes coupled with two-dimensional arrays of small BGO scintillator blocks make simple and compact position-sensitive {gamma}-ray detectors. With a sample-detector distance of 5m, an angular resolution of 1.1 mrad FWHM and a coincidence count rate of {approx}2.4 c.p.s. per mCi are obtained. Its performance is demonstrated by the result of a test measurement for KI crystal in which non-localized positronium exists at low temperatures. (author)

  6. A hybrid tandem solar cell based on hydrogenated amorphous silicon and dye-sensitized TiO{sub 2} film

    Energy Technology Data Exchange (ETDEWEB)

    Hao Sancun [Institute of Materials Physical Chemistry, Huaqiao University, Quanzhou, 362021 (China); Institute of Photo-Electronics of Nankai University, Tianjin 300071 (China); Jiangsu Shuangdeng Group Co. Ltd, Thaizhou, Jiangsu, 225526 (China); Wu Jihuai, E-mail: jhwu@hqu.edu.cn [Institute of Materials Physical Chemistry, Huaqiao University, Quanzhou, 362021 (China); Sun Zhonglin [Institute of Photo-Electronics of Nankai University, Tianjin 300071 (China)

    2012-01-01

    Hydrogenated amorphous silicon film (a-Si:H) as top cell is introduced to dye-sensitized titanium dioxide nanocrystalline solar cell (DSSC) as bottom cell to assemble a hybrid tandem solar cell. The hybrid tandem solar cell fabricated with the thicknesses a-Si:H layer of 235 nm, ZnO/Pt interlayer of 100 nm and DSSC layer of 8.5 {mu}m achieves a photo-to-electric energy conversion efficiency of 8.31%, a short circuit current density of 10.61 mA{center_dot}cm{sup -2} and an open-circuit voltage of 1.45 V under a simulated solar light irradiation of 100 mW{center_dot}cm{sup -2}.

  7. High Sensitivity pH Sensor Based on Porous Silicon (PSi) Extended Gate Field-Effect Transistor.

    Science.gov (United States)

    Al-Hardan, Naif H; Abdul Hamid, Muhammad Azmi; Ahmed, Naser M; Jalar, Azman; Shamsudin, Roslinda; Othman, Norinsan Kamil; Kar Keng, Lim; Chiu, Weesiong; Al-Rawi, Hamzah N

    2016-06-07

    In this study, porous silicon (PSi) was prepared and tested as an extended gate field-effect transistor (EGFET) for pH sensing. The prepared PSi has pore sizes in the range of 500 to 750 nm with a depth of approximately 42 µm. The results of testing PSi for hydrogen ion sensing in different pH buffer solutions reveal that the PSi has a sensitivity value of 66 mV/pH that is considered a super Nernstian value. The sensor considers stability to be in the pH range of 2 to 12. The hysteresis values of the prepared PSi sensor were approximately 8.2 and 10.5 mV in the low and high pH loop, respectively. The result of this study reveals a promising application of PSi in the field for detecting hydrogen ions in different solutions.

  8. High Sensitivity pH Sensor Based on Porous Silicon (PSi Extended Gate Field-Effect Transistor

    Directory of Open Access Journals (Sweden)

    Naif H. Al-Hardan

    2016-06-01

    Full Text Available In this study, porous silicon (PSi was prepared and tested as an extended gate field-effect transistor (EGFET for pH sensing. The prepared PSi has pore sizes in the range of 500 to 750 nm with a depth of approximately 42 µm. The results of testing PSi for hydrogen ion sensing in different pH buffer solutions reveal that the PSi has a sensitivity value of 66 mV/pH that is considered a super Nernstian value. The sensor considers stability to be in the pH range of 2 to 12. The hysteresis values of the prepared PSi sensor were approximately 8.2 and 10.5 mV in the low and high pH loop, respectively. The result of this study reveals a promising application of PSi in the field for detecting hydrogen ions in different solutions.

  9. A position sensitive parallel plate avalanche fission detector for use in particle induced fission coincidence measurements

    NARCIS (Netherlands)

    Plicht, J. van der

    1980-01-01

    A parallel plate avalanche detector developed for the detection of fission fragments in particle induced fission reactions is described. The active area is 6 × 10 cm2; it is position sensitive in one dimension with a resolution of 2.5 mm. The detector can withstand a count rate of 25000 fission

  10. Face Inversion Disproportionately Disrupts Sensitivity to Vertical over Horizontal Changes in Eye Position

    Science.gov (United States)

    Crookes, Kate; Hayward, William G.

    2012-01-01

    Presenting a face inverted (upside down) disrupts perceptual sensitivity to the spacing between the features. Recently, it has been shown that this disruption is greater for vertical than horizontal changes in eye position. One explanation for this effect proposed that inversion disrupts the processing of long-range (e.g., eye-to-mouth distance)…

  11. Sensitivity Analyses of Alternative Methods for Disposition of High-Level Salt Waste: A Position Statement

    International Nuclear Information System (INIS)

    Harris, S.P.; Tuckfield, R.C.

    1998-01-01

    This position paper provides the approach and detail pertaining to a sensitivity analysis for the Phase II definition of weighted evaluation criteria weights and utility function values on the total utility scores for each Initial List alternative due to uncertainty and bias in engineering judgment

  12. Method and apparatus for formation logging using position sensitive neutron detectors

    International Nuclear Information System (INIS)

    Gadken, L.L.

    1986-01-01

    This patent describes a method for logging earth formations using position sensitive neutron detectors. The method consists of: 1) Irradiation of earth formations in the vicinity of a well borehole with a source of fast neutrons. 2) At four longitudinally spaced distances from the neutron source in the borehole, the epithermal neutron population is detected. Each of the four separate populations is detected in an epithermally sensitive and substantially thermally insensitive portion of the same position sensitive neutron detector. A representative signal from each is then individually generated. 3) First, second, third, and fourth neutron population representative signals are combined. They derive a simultaneous measurement signal. This signal is functionally related to the porosity and also a signal functionally related to a neutron characteristic length of the earth formations in the vicinity of the borehole

  13. The design of a position-sensitive thermal-neutron detector

    International Nuclear Information System (INIS)

    Zhang Yi; Chen Ziyu; Shen Ji

    2007-01-01

    We design a type of position-sensitive thermal-neutron detector. The design is based on the nuclear reaction 10 B(n, α) 7 Li, and solid boron-10 is used as the target material while the alpha and lithium-7 particles from the reaction are caught as the source of position information of the original neutrons. With the help of MCNP software, we simulate the distribution of alpha particles in the boron target, which leads to the optimal thickness of target, physical efficiency and position resolution. (authors)

  14. Experimental dead time corrections for a linear position-sensitive proportional counter

    International Nuclear Information System (INIS)

    Yelon, W.B.; Tompson, C.W.; Mildner, D.F.R.; Berliner, R.; Missouri Univ., Columbia

    1984-01-01

    Two simple counters included in the charge-digitization circuitry of a position-sensitive proportional counter using the charge division method for position encoding have enabled us to determine the dead time losses for the system. An interesting positional dependence of the dead time tau is observed, which agrees with a simple model. The system enables us to correct the experimental data for dead time and to be indifferent to the relatively slow analog-to-digital converters used in the system. (orig.)

  15. Tests of crossed-wire position sensitive photomultipliers for scintillating fiber particle tracking

    International Nuclear Information System (INIS)

    Perdrisat, C.F.; Koechner, D.; Majewski, S.; Pourang, R.; Wilson, C.D.; Zorn, C.

    1995-01-01

    Several applications of two Hamamatsu position sensitive photomultiplier tubes to the detection of high energy particles with scintillating fibers are discussed. The PMTs are of the multiwire anode grid design, type R2486 and R4135. These tubes were tested with both single samples and arrays of 2 and 3 mm diameter scintillating fibers. Measurements of position resolution of the PMTs using either the charge digitization or the delay line readout techniques were made. The results indicate an intrinsic inability of the technique to reconstruct the actual position of a fiber on the photocathode when its location falls halfway between two grid wires. A way to overcome this limit is suggested. (orig.)

  16. Functionalized graphene/silicon chemi-diode H2 sensor with tunable sensitivity

    International Nuclear Information System (INIS)

    Uddin, Md Ahsan; Singh, Amol Kumar; Sudarshan, Tangali S; Koley, Goutam

    2014-01-01

    A reverse bias tunable Pd- and Pt-functionalized graphene/Si heterostructure Schottky diode H 2 sensor has been demonstrated. Compared to the graphene chemiresistor sensor, the chemi-diode sensor offers more than one order of magnitude higher sensitivity as the molecular adsorption induced Schottky barrier height change causes the heterojunction current to vary exponentially in reverse bias. The reverse bias operation also enables low power consumption, as well as modulation of the atomically thin graphene’s Fermi level, leading to tunable sensitivity and detection of H 2 down to the sub-ppm range. (paper)

  17. Functionalized graphene/silicon chemi-diode H₂ sensor with tunable sensitivity.

    Science.gov (United States)

    Uddin, Md Ahsan; Singh, Amol Kumar; Sudarshan, Tangali S; Koley, Goutam

    2014-03-28

    A reverse bias tunable Pd- and Pt-functionalized graphene/Si heterostructure Schottky diode H2 sensor has been demonstrated. Compared to the graphene chemiresistor sensor, the chemi-diode sensor offers more than one order of magnitude higher sensitivity as the molecular adsorption induced Schottky barrier height change causes the heterojunction current to vary exponentially in reverse bias. The reverse bias operation also enables low power consumption, as well as modulation of the atomically thin graphene's Fermi level, leading to tunable sensitivity and detection of H₂ down to the sub-ppm range.

  18. Microchannel-connected SU-8 honeycombs by single-step projection photolithography for positioning cells on silicon oxide nanopillar arrays

    International Nuclear Information System (INIS)

    Larramendy, Florian; Paul, Oliver; Blatche, Marie Charline; Mazenq, Laurent; Laborde, Adrian; Temple-Boyer, Pierre

    2015-01-01

    We report on the fabrication, functionalization and testing of SU-8 microstructures for cell culture and positioning over large areas. The microstructure consists of a honeycomb arrangement of cell containers interconnected by microchannels and centered on nanopillar arrays designed for promoting cell positioning. The containers have been dimensioned to trap single cells and, with a height of 50 µm, prevent cells from escaping. The structures are fabricated using a single ultraviolet photolithography exposure with focus depth in the lower part of the SU-8 resist. With optimized process parameters, microchannels of various aspect ratios are thus produced. The cell containers and microchannels serve for the organization of axonal growth between neurons. The roughly 2 µm-high and 500 nm-wide nanopillars are made of silicon oxide structured by deep reactive ion etching. In future work, beyond their cell positioning purpose, the nanopillars could be functionalized as sensors. The proof of concept of the novel microstructure for organized cell culture is given by the successful growth of interconnected PC12 cells. Promoted by the honeycomb geometry, a dense network of interconnections between the cells has formed and the intended intimate contact of cells with the nanopillar arrays was observed by scanning electron microscopy. This proves the potential of these new devices as tools for the controlled cell growth in an interconnected container system with well-defined 3D geometry. (paper)

  19. Sensitivity of the Positive and Negative Syndrome Scale (PANSS) in Detecting Treatment Effects via Network Analysis.

    Science.gov (United States)

    Esfahlani, Farnaz Zamani; Sayama, Hiroki; Visser, Katherine Frost; Strauss, Gregory P

    2017-12-01

    Objective: The Positive and Negative Syndrome Scale is a primary outcome measure in clinical trials examining the efficacy of antipsychotic medications. Although the Positive and Negative Syndrome Scale has demonstrated sensitivity as a measure of treatment change in studies using traditional univariate statistical approaches, its sensitivity to detecting network-level changes in dynamic relationships among symptoms has yet to be demonstrated using more sophisticated multivariate analyses. In the current study, we examined the sensitivity of the Positive and Negative Syndrome Scale to detecting antipsychotic treatment effects as revealed through network analysis. Design: Participants included 1,049 individuals diagnosed with psychotic disorders from the Phase I portion of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) study. Of these participants, 733 were clinically determined to be treatment-responsive and 316 were found to be treatment-resistant. Item level data from the Positive and Negative Syndrome Scale were submitted to network analysis, and macroscopic, mesoscopic, and microscopic network properties were evaluated for the treatment-responsive and treatment-resistant groups at baseline and post-phase I antipsychotic treatment. Results: Network analysis indicated that treatment-responsive patients had more densely connected symptom networks after antipsychotic treatment than did treatment-responsive patients at baseline, and that symptom centralities increased following treatment. In contrast, symptom networks of treatment-resistant patients behaved more randomly before and after treatment. Conclusions: These results suggest that the Positive and Negative Syndrome Scale is sensitive to detecting treatment effects as revealed through network analysis. Its findings also provide compelling new evidence that strongly interconnected symptom networks confer an overall greater probability of treatment responsiveness in patients with

  20. Current status and requirements for position-sensitive detectors in medicine

    CERN Document Server

    Speller, R

    2002-01-01

    This review considers the current status of detector developments for medical imaging using ionising radiation. This field is divided into two major areas; the use of X-rays for transmission imaging and the use of radioactive tracers in emission imaging (nuclear medicine). Until recently, most detector developments were for applications in nuclear medicine. However, in the past 5 years new developments in large area, X-ray-sensitive detectors have meant that both application domains are equally served. In X-ray imaging, work in CT and mammography are chosen as examples of sensor developments. Photodiode arrays in multi-slice spiral CT acquisitions are described and for mammography the use of amorphous silicon flat panel arrays is considered. The latter is an excellent example where new detector developments have required a re-think of traditional imaging methods. In gamma-ray imaging the recent developments in small area, task-specific cameras are described. Their limitations and current proposals to overcome...

  1. Analysis of asymmetric resonance response of thermally excited silicon micro-cantilevers for mass-sensitive nanoparticle detection

    Science.gov (United States)

    Bertke, Maik; Hamdana, Gerry; Wu, Wenze; Suryo Wasisto, Hutomo; Uhde, Erik; Peiner, Erwin

    2017-06-01

    In this paper, the asymmetric resonance frequency (f 0) responses of thermally in-plane excited silicon cantilevers for a pocket-sized, cantilever-based airborne nanoparticle detector (Cantor) are analysed. By measuring the shift of f 0 caused by the deposition of nanoparticles (NPs), the cantilevers are used as a microbalance. The cantilever sensors are low cost manufactured from silicon by bulk-micromachining techniques and contain an integrated p-type heating actuator and a sensing piezoresistive Wheatstone bridge. f 0 is tracked by a homemade phase-locked loop (PPL) for real-time measurements. To optimize the sensor performance, a new cantilever geometry was designed, fabricated and characterized by its frequency responses. The most significant characterisation parameters of our application are f 0 and the quality factor (Q), which have high influences on sensitivity and efficiency of the NP detector. Regarding the asymmetric resonance signal, a novel fitting function based on the Fano resonance replacing the conventionally used function of the simple harmonic oscillator and a method to calculate Q by its fitting parameters were developed for a quantitative evaluation. To obtain a better understanding of the resonance behaviours, we analysed the origin of the asymmetric line shapes. Therefore, we compared the frequency response of the on-chip thermal excitation with an external excitation using an in-plane piezo actuator. In correspondence to the Fano effect, we could reconstruct the measured resonance curves by coupling two signals with constant amplitude and the expected signal of the cantilever, respectively. Moreover, the phase of the measurement signal can be analysed by this method, which is important to understand the locking process of the PLL circuit. Besides the frequency analysis, experimental results and calibration measurements with different particle types are presented. Using the described analysis method, decent results to optimize a next

  2. Facile synthesis of silicon carbide-titanium dioxide semiconducting nanocomposite using pulsed laser ablation technique and its performance in photovoltaic dye sensitized solar cell and photocatalytic water purification

    Energy Technology Data Exchange (ETDEWEB)

    Gondal, M.A., E-mail: magondal@kfupm.edu.sa [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Ilyas, A.M. [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Baig, Umair [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Center of Excellence for Scientific Research Collaboration with MIT, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2016-08-15

    Highlights: • SiC–TiO{sub 2} semiconducting nanocomposites synthesized by nanosecond PLAL technique. • Synthesized nanocomposites were morphologically and optically characterized. • Nanocomposites were applied for the photocatalytic degradation of toxic organic dye. • Photovoltaic performance was investigated in dye sensitized solar cell. - Abstract: Separation of photo-generated charge carriers (electron and holes) is a major approach to improve the photovoltaic and photocatalytic performance of metal oxide semiconductors. For harsh environment like high temperature applications, ceramic like silicon carbide is very prominent. In this work, 10%, 20% and 40% by weight of pre-oxidized silicon carbide was coupled with titanium dioxide (TiO{sub 2}) to form nanocomposite semiconductor via elegant pulsed laser ablation in liquid technique using second harmonic 532 nm wavelength of neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. In addition, the effect of silicon carbide concentration on the performance of silicon carbide-titanium dioxide nanocomposite as photo-anode in dye sensitized solar cell and as photocatalyst in photodegradation of methyl orange dye in water was also studied. The result obtained shows that photo-conversion efficiency of the dye sensitized solar cell was improved from 0.6% to 1.65% and the percentage of methyl orange dye removed was enhanced from 22% to 77% at 24 min under ultraviolet–visible solar spectrum in the nanocomposite with 10% weight of silicon carbide. This remarkable performance enhancement could be due to the improvement in electron transfer phenomenon by the presence of silicon carbide on titanium dioxide.

  3. Charge-sensitive poly-silicon TFT amplifiers for a-Si:H pixel particle detectors

    International Nuclear Information System (INIS)

    Cho, G.; Perez-Mendez, V.; Hack, M.; Lewis, A.

    1992-04-01

    Prototype charge-sensitive poly-Si TFT amplifiers have been made for the amplification of signals (from an a-Si:H pixel diode used as an ionizing particle detector). They consist of a charge-sensitive gain stage, a voltage gain stage and a source follower output stage. The gain-bandwidth product of the amplifier is ∼ 300 MHz. When the amplifier is connected to a pixel detector of 0.2 pF, it gives a charge-to-voltage gain of ∼ 0.02 mV/electrons with a pulse rise time less than 100 nsec. An equivalent noise charge of the front-end TFT is ∼ 1000 electrons for a shaping time of 1 μsec

  4. Ultrafast Readout of Scintillating Fibres Using Upgraded Position-Sensitive Photomultipliers

    CERN Multimedia

    2002-01-01

    % RD-17 \\\\ \\\\To design a high rate topological trigger device for the future DIRAC Experiment at CERN an extensive work is in progress on a scintillating-fibre detector using a position-sensitive photomultiplier. Several detector prototypes with different lengths ($<$~50~cm) of sensitive area have been tested at T7S~PS beam. \\\\ \\\\With 0.5~mm diameter fibres a spatial resolution of $\\sim$125~$\\mu$m was obtained with a detection efficiency higher than 95\\%. The time resolution is $\\sim$600~ps, and the track position is properly digitized in real time (about 10~ns) by multi-channel peak sensing circuit. Based on experimental data simulations were also performed a comparison of different types of front-end electronics for multi-channel readout.

  5. Cerium doped GSO scintillators and its application to position sensitive detectors

    International Nuclear Information System (INIS)

    Ishibashi, H.; Shimizu, K.; Susa, K.; Kubota, S.

    1989-01-01

    The dependence of the light output and the decay times of Ce doped Gd/sub 2/SiO/sub 5/ on Ce concentration is measured. By using the difference in decay times on Ce concentration for GSO(Ce), the combination of different concentration of GSO(Ce) scintillators is shown to be useful as position sensitive detectors. A Ce doped Gd/sub 2/SiO/sub 5/ (GSO(Ce)) single crystal is an excellent scintillator featuring, a large light output, a short decay time and a high absorption coefficient. Further investigation aimed at its implementation to scintillators has been carried out previously. An application of the GSO(Ce) scintillators to the gamma-ray detectors of positron emission computed tomography has also been shown. The authors have investigated the dependence of its scintillation properties on the Ce concentration and its application to position sensitive detectors

  6. Position sensitive proportional counter for measurement of tritium labelled gas movement

    International Nuclear Information System (INIS)

    Mori, Chizuo; Nakamoto, Makihiko; Uritani, Akira; Watanabe, Tamaki

    1984-01-01

    A position sensitive proportional counter of a charge division type with a single resistive anode wire was constructed for the measurement of the movement of 3 H labelled gas which is flowing or diffusing in a pipe. The introduction of resistors between the anode wire and pre-amplifiers brought a uniform detection efficiency for 3 H β-rays throughout the counter. The position resolution was 3.1 mm FWHM. Detection efficiency was almost 100% uniformly over about 700 mm in the total anode length of 740 mm. The movement of 3 H labelled gas could be measured effectively. (author)

  7. Coplanar-grid CdZnTe detector with three-dimensional position sensitivity

    International Nuclear Information System (INIS)

    Luke, P.N.; Amman, M.; Lee, J.S.; Yaver, H.

    1998-06-01

    A 3-dimensional position-sensitive coplanar-grid detector design for use with compound semiconductors is described. This detector design maintains the advantage of a coplanar-grid detector in which good energy resolution can be obtained from materials with poor charge transport. Position readout in two dimensions is accomplished using proximity-sensing electrodes adjacent to the electron-collecting grid electrode of the detector. Additionally, depth information is obtained by taking the ratio of the amplitudes of the collecting grid signal and the cathode signal. Experimental results from a prototype CdZnTe detector are presented

  8. Reduction of digital errors of digital charge division type position-sensitive detectors

    International Nuclear Information System (INIS)

    Uritani, A.; Yoshimura, K.; Takenaka, Y.; Mori, C.

    1994-01-01

    It is well known that ''digital errors'', i.e. differential non-linearity, appear in a position profile of radiation interactions when the profile is obtained with a digital charge-division-type position-sensitive detector. Two methods are presented to reduce the digital errors. They are the methods using logarithmic amplifiers and a weighting function. The validities of these two methods have been evaluated mainly by computer simulation. These methods can considerably reduce the digital errors. The best results are obtained when both methods are applied. ((orig.))

  9. High speed USB data logger for position sensitive detector data acquisition

    International Nuclear Information System (INIS)

    Poudel, S.K.; Kulkarni, V.B.; Kumar, Santosh; Chandak, R.M.; Krishna, P.S.R.; Mukhopadhyay, R.

    2010-01-01

    Ratio ADC (RDC) module used in neutron Position Sensitive Detector (PSD) data acquisition, gives digital code signifying the position of neutron event. A High Speed USB based RDC Data Logger card has been made for logging data from multiple RDCs to PC. A CPLD on the card continuously polls the RDCs for data, and fills it in the FIFO memory of a high speed USB microcontroller. A VC++ program for neutron scattering experiments reads event codes from FIFO of microcontroller and builds spectrum on PC. This program sweeps physical parameters of sample and collects PSD data for pre-determined monitor counts. (author)

  10. A new position-sensitive detector for thermal and epithermal neutrons

    International Nuclear Information System (INIS)

    Jeavons, A.P.; Ford, N.L.; Lindberg, B.; Sachot, R.

    1977-01-01

    A new two-dimensional position-sensitive neutron detector is described. It is based on (n,γ) neutron resonance capture in a foil with subsequent detection of internal conversion electrons with a high-density proportional chamber. Large-area detectors with a 1 mm spatial resolution are feasible. A detection efficiency of 50% is possible for thermal neutrons using gadolinium-157 foil and for epithermal neutrons using hafnium-177. (Auth.)

  11. Angle-resolved ion TOF spectrometer with a position sensitive detector

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Norio [Electrotechnical Lab., Tsukuba, Ibaraki (Japan); Heiser, F; Wieliczec, K; Becker, U

    1996-07-01

    A angle-resolved ion time-of-flight mass spectrometer with a position sensitive anode has been investigated. Performance of this spectrometer has been demonstrated by measuring an angular distribution of a fragment ion pair, C{sup +} + O{sup +}, from CO at the photon energy of 287.4 eV. The obtained angular distribution is very close to the theoretically expected one. (author)

  12. The local lymph node assay: current position in the regulatory classification of skin sensitizing chemicals.

    Science.gov (United States)

    Basketter, David A; Gerberick, G Frank; Kimber, Ian

    2007-01-01

    The local lymph node assay (LLNA) is being used increasingly in the identification of skin sensitizing chemicals for regulatory purposes. In the context of new chemicals legislation (REACH) in Europe, it is the preferred assay. The rationale for this is that the LLNA quantitative and objective approach to skin sensitization testing allied with the important animal welfare benefits that the method offers. However, as with certain guinea pig sensitization tests before it, this increasing use also brings experience with an increasingly wide range of industrial and other chemicals where the outcome of the assay does not always necessarily meet with the expectations of those conducting it. Sometimes, the result appears to be a false negative, but rather more commonly, the complaint is that the chemical represents a false positive. Against this background we have here reviewed a number of instances where false positive and false negative results have been described and have sought to reconcile science with expectation. Based on these analyses, it is our conclusion that false positives and false negatives do occur in the LLNA, as they do with any other skin sensitization assay (and indeed with all tests used for hazard identification), and that this occurs for a number of reasons. We further conclude, however, that false positive results in the LLNA, as with the guinea pig maximization test, arise most commonly via failure to distinguish what is scientifically correct from that which is unpalatable. The consequences of this confusion are discussed in the article, particularly in relation to the need to integrate both potency measurement and risk assessments into classification and labelling schemes that aim to manage potential risks to human health.

  13. Design and performance of vacuum capable detector electronics for linear position sensitive neutron detectors

    International Nuclear Information System (INIS)

    Riedel, R.A.; Cooper, R.G.; Funk, L.L.; Clonts, L.G.

    2012-01-01

    We describe the design and performance of electronics for linear position sensitive neutron detectors. The eight tube assembly requires 10 W of power and can be controlled via digital communication links. The electronics can be used without modification in vacuum. Using a transimpedance amplifier and gated integration, we achieve a highly linear system with coefficient of determinations of 0.9999 or better. Typical resolution is one percent of tube length.

  14. Design and performance of vacuum capable detector electronics for linear position sensitive neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Riedel, R.A., E-mail: riedelra@ornl.gov [Oak Ridge National Laboratories, Oak Ridge, TN 37830 (United States); Cooper, R.G.; Funk, L.L.; Clonts, L.G. [Oak Ridge National Laboratories, Oak Ridge, TN 37830 (United States)

    2012-02-01

    We describe the design and performance of electronics for linear position sensitive neutron detectors. The eight tube assembly requires 10 W of power and can be controlled via digital communication links. The electronics can be used without modification in vacuum. Using a transimpedance amplifier and gated integration, we achieve a highly linear system with coefficient of determinations of 0.9999 or better. Typical resolution is one percent of tube length.

  15. Test of a position-sensitive photomultiplier for fast scintillating fiber detector read-out

    International Nuclear Information System (INIS)

    Baehr, J.; Hoffmann, B.; Luedecke, H.; Nahnhauer, R.; Pohl, M.; Roloff, H.E.

    1993-01-01

    A position-sensitive photomultiplier with 256 anode pixels has been used to read out scintillating fibers excited by light emitting diodes, electrons from a β-source and a 5 GeV electron beam. Measurements have been done within a magnetic field up to 0.6 T. Tracking and electromagnetic shower detection capabilities of a simple fiber detector have been studied. (orig.)

  16. DIAGNOSIS OF CULTURE POSITIVE URINARY TRACT INFECTIONS AND THEIR ANTIMICROBIAL SENSITIVITY PROFILE IN TERTIARY CARE CENTRE

    Directory of Open Access Journals (Sweden)

    Prince Sreekumar Pius

    2016-12-01

    Full Text Available BACKGROUND Urinary tract infection is very common all over the world and in India more than 10 million cases are reported per year. It is one of the common infections diagnosed in the outpatients as well as the hospitalised patients. Empirical treatment of community acquired urinary tract infections are determined by the antibiotic sensitivity in a population. This study was conducted to determine the antimicrobial sensitivity amongst the uropathogens to help establish local guidelines on treatment of urinary tract infection. MATERIALS AND METHODS In this study, we collected 1306 samples from patients in whom we suspected to have urinary tract infection based on clinical signs and symptoms (e.g. with fever (greater than 38°C without another explanation or from a patient who had at least one urinary symptom (dysuria, urgency, frequency, or suprapubic pain or tenderness in our hospital during January 2016-June 2016. RESULTS Urine cultures were positive for 18% of the patients. Among these cultures, Klebsiella pneumonia (41%, Escherichia coli (35% and Pseudomonas aeruginosa (7% were the common organisms found. Highest antimicrobial sensitivity amongst these pathogens was found with cefoperazone/sulbactam and amikacin. CONCLUSION Cefoperazone/sulbactam and amikacin were the highly sensitive systemic antibiotics while ciprofloxacin and norfloxacin were the sensitive oral antibiotics in our locality.

  17. Range position and climate sensitivity: The structure of among-population demographic responses to climatic variation

    Science.gov (United States)

    Amburgey, Staci M.; Miller, David A. W.; Grant, Evan H. Campbell; Rittenhouse, Tracy A. G.; Benard, Michael F.; Richardson, Jonathan L.; Urban, Mark C.; Hughson, Ward; Brand, Adrianne B,; Davis, Christopher J.; Hardin, Carmen R.; Paton, Peter W. C.; Raithel, Christopher J.; Relyea, Rick A.; Scott, A. Floyd; Skelly, David K.; Skidds, Dennis E.; Smith, Charles K.; Werner, Earl E.

    2018-01-01

    Species’ distributions will respond to climate change based on the relationship between local demographic processes and climate and how this relationship varies based on range position. A rarely tested demographic prediction is that populations at the extremes of a species’ climate envelope (e.g., populations in areas with the highest mean annual temperature) will be most sensitive to local shifts in climate (i.e., warming). We tested this prediction using a dynamic species distribution model linking demographic rates to variation in temperature and precipitation for wood frogs (Lithobates sylvaticus) in North America. Using long-term monitoring data from 746 populations in 27 study areas, we determined how climatic variation affected population growth rates and how these relationships varied with respect to long-term climate. Some models supported the predicted pattern, with negative effects of extreme summer temperatures in hotter areas and positive effects on recruitment for summer water availability in drier areas. We also found evidence of interacting temperature and precipitation influencing population size, such as extreme heat having less of a negative effect in wetter areas. Other results were contrary to predictions, such as positive effects of summer water availability in wetter parts of the range and positive responses to winter warming especially in milder areas. In general, we found wood frogs were more sensitive to changes in temperature or temperature interacting with precipitation than to changes in precipitation alone. Our results suggest that sensitivity to changes in climate cannot be predicted simply by knowing locations within the species’ climate envelope. Many climate processes did not affect population growth rates in the predicted direction based on range position. Processes such as species-interactions, local adaptation, and interactions with the physical landscape likely affect the responses we observed. Our work highlights the

  18. Positive words or negative words: whose valence strength are we more sensitive to?

    Science.gov (United States)

    Yang, Jiemin; Zeng, Jing; Meng, Xianxin; Zhu, Liping; Yuan, Jiajin; Li, Hong; Yusoff, Nasir

    2013-10-02

    The present study investigates the human brains' sensitivity to the valence strength of emotionally positive and negative chinese words. Event-Related Potentials were recorded, in two different experimental sessions, for Highly Positive (HP), Mildly Positive (MP) and neutral (NP) words and for Highly Negative (HN), Mildly Negative (MN) and neutral (NN) words, while subjects were required to count the number of words, irrespective of word meanings. The results showed a significant emotion effect in brain potentials for both HP and MP words, and the emotion effect occurred faster for HP words than MP words: HP words elicited more negative deflections than NP words in N2 (250-350 ms) and P3 (350-500 ms) amplitudes, while MP words elicited a significant emotion effect in P3, but not in N2, amplitudes. By contrast, HN words elicited larger amplitudes than NN words in N2 but not in P3 amplitudes, whereas MN words produced no significant emotion effect across N2 and P3 components. Moreover, the size of emotion-neutral differences in P3 amplitudes was significantly larger for MP compared to MN words. Thus, the human brain is reactive to both highly and mildly positive words, and this reactivity increased with the positive valence strength of the words. Conversely, the brain is less reactive to the valence of negative relative to positive words. These results suggest that human brains are equipped with increased sensitivity to the valence strength of positive compared to negative words, a type of emotional stimuli that are well known for reduced arousal. © 2013 Elsevier B.V. All rights reserved.

  19. Single-Electron and Single-Photon Sensitivity with a Silicon Skipper CCD

    Science.gov (United States)

    Tiffenberg, Javier; Sofo-Haro, Miguel; Drlica-Wagner, Alex; Essig, Rouven; Guardincerri, Yann; Holland, Steve; Volansky, Tomer; Yu, Tien-Tien

    2017-09-01

    We have developed ultralow-noise electronics in combination with repetitive, nondestructive readout of a thick, fully depleted charge-coupled device (CCD) to achieve an unprecedented noise level of 0.068 e- rms /pixel . This is the first time that discrete subelectron readout noise has been achieved reproducible over millions of pixels on a stable, large-area detector. This enables the contemporaneous, discrete, and quantized measurement of charge in pixels, irrespective of whether they contain zero electrons or thousands of electrons. Thus, the resulting CCD detector is an ultra-sensitive calorimeter. It is also capable of counting single photons in the optical and near-infrared regime. Implementing this innovative non-destructive readout system has a negligible impact on CCD design and fabrication, and there are nearly immediate scientific applications. As a particle detector, this CCD will have unprecedented sensitivity to low-mass dark matter particles and coherent neutrino-nucleus scattering, while future astronomical applications may include direct imaging and spectroscopy of exoplanets.

  20. A fast large-area position-sensitive time-of-flight neutron detection system

    International Nuclear Information System (INIS)

    Crawford, R.K.; Haumann, J.R.

    1989-01-01

    A new position-sensitive time-of-flight neutron detection and histograming system has been developed for use at the Intense Pulsed Neutron Source. Spatial resolution of roughly 1 cm x 1 cm and time-of-flight resolution of ∼1 μsec are combined in a detection system which can ultimately be expanded to cover several square meters of active detector area. This system is based on the use of arrays of cylindrical one-dimensional position-sensitive proportional counters, and is capable of collecting the x-y-t data and sorting them into histograms at time-averaged data rates up to ∼300,000 events/sec over the full detector area and with instantaneous data rates up to more than fifty times that. Numerous hardware features have been incorporated to facilitate initial tuning of the position encoding, absolute calibration of the encoded positions, and automatic testing for drifts. 7 refs., 11 figs., 1 tabs

  1. Recent developments and applications of fast position-sensitive gas detectors

    International Nuclear Information System (INIS)

    Sauli, Fabio

    1999-01-01

    The introduction, 30 years ago, of the multiwire proportional chamber initiated a very active and fruitful period of development of fast gas detectors. Performing position-sensitive devices have been perfected, for the needs of elementary particle physics and for applications in medical diagnostics, biology, material analysis. The high rate performance of wire counters, limited by positive ions accumulation, was largely improved with the introduction of the micro-strip gas chamber, capable of achieving position accuracies of few tens of microns at radiation fluxes exceeding 1 MHz/mm 2 . The micro-strip chamber properties have been extensively studied in view of large scale use in high luminosity experiments; some interesting applications in other fields will be described here. Originally conceived as a gain booster to solve reliability problems met with micro-strips, the gas electron multiplier was invented about a year and a half ago. Progress made with high gain models is leading to a new concept in gas detectors, powerful yet cheap and reliable. Possible developments and applications will be discussed: large area position-sensitive photo detectors and X-ray imagers, including devices with non-planar geometry suited to spectrometers and crystal diffraction studies

  2. Head position in the MEG helmet affects the sensitivity to anterior sources.

    Science.gov (United States)

    Marinkovic, K; Cox, B; Reid, K; Halgren, E

    2004-11-30

    Current MEG instruments derive the whole-head coverage by utilizing a helmet-shaped opening at the bottom of the dewar. These helmets, however, are quite a bit larger than most people's heads so subjects commonly lean against the back wall of the helmet in order to maintain a steady position. In such cases the anterior brain sources may be too distant to be picked up by the sensors reliably. Potential "invisibility" of the frontal and anterior temporal sources may be particularly troublesome for the studies of cognition and language, as they are subserved significantly by these areas. We examined the sensitivity of the distributed anatomically-constrained MEG (aMEG) approach to the head position ("front" vs. "back") secured within a helmet with custom-tailored bite-bars during a lexical decision task. The anterior head position indeed resulted in much greater sensitivity to language-related activity in frontal and anterior temporal locations. These results emphasize the need to adjust the head position in the helmet in order to maximize the "visibility" of the sources in the anterior brain regions in cognitive and language tasks.

  3. Positive and negative gain exceeding unity magnitude in silicon quantum well metal-oxide-semiconductor transistors

    Science.gov (United States)

    Hu, Gangyi; Wijesinghe, Udumbara; Naquin, Clint; Maggio, Ken; Edwards, H. L.; Lee, Mark

    2017-10-01

    Intrinsic gain (AV) measurements on Si quantum well (QW) n-channel metal-oxide-semiconductor (NMOS) transistors show that these devices can have |AV| > 1 in quantum transport negative transconductance (NTC) operation at room temperature. QW NMOS devices were fabricated using an industrial 45 nm technology node process incorporating ion implanted potential barriers to define a lateral QW in the conduction channel under the gate. While NTC at room temperature arising from transport through gate-controlled QW bound states has been previously established, it was unknown whether the quantum NTC mechanism could support gain magnitude exceeding unity. Bias conditions were found giving both positive and negative AV with |AV| > 1 at room temperature. This result means that QW NMOS devices could be useful in amplifier and oscillator applications.

  4. High-Sensitivity and Low-Power Flexible Schottky Hydrogen Sensor Based on Silicon Nanomembrane.

    Science.gov (United States)

    Cho, Minkyu; Yun, Jeonghoon; Kwon, Donguk; Kim, Kyuyoung; Park, Inkyu

    2018-04-18

    High-performance and low-power flexible Schottky diode-based hydrogen sensor was developed. The sensor was fabricated by releasing Si nanomembrane (SiNM) and transferring onto a plastic substrate. After the transfer, palladium (Pd) and aluminum (Al) were selectively deposited as a sensing material and an electrode, respectively. The top-down fabrication process of flexible Pd/SiNM diode H 2 sensor is facile compared to other existing bottom-up fabricated flexible gas sensors while showing excellent H 2 sensitivity (Δ I/ I 0 > 700-0.5% H 2 concentrations) and fast response time (τ 10-90 = 22 s) at room temperature. In addition, selectivity, humidity, and mechanical tests verify that the sensor has excellent reliability and robustness under various environments. The operating power consumption of the sensor is only in the nanowatt range, which indicates its potential applications in low-power portable and wearable electronics.

  5. Pulse shape discrimination with silicon detectors using charge and current-sensitive preamplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Hamrita, H.; Rauly, E.; Blumenfeld, Y.; Borderie, B.; Chabot, M.; Edelbruck, P.; Lavergne, L.; Le Bris, J.; Le Neindre, N.; Richard, A.; Rivet, M.F.; Scarpaci, J.A.; Barbey, S.; Becheva, E.; Bzyl, F.R.; D' Esesquelles, P.; Galichet, E.; Lalu, G.; Martinet, G.; Pierre, S. [Institut de Physique Nucleaire, IN2P3-CNRS, 91 - Orsay (France); Legou, Th.; Tillier, J.; Bocage, F.; Bougault, R.; Carniol, B.; Cussol, D.; Etasse, D.; Grevy, S.; Lopez, O.; Tamain, B.; Vient, E. [Caen Univ., LPC, IN2P3-CNRS, ENSI, 14 - Caen (France); Galichet, E. [Conservatoire National des Arts et Metier, 75 - Paris (France); Guinet, D.; Lautesse, Ph. [Villeurbanne Univ., Institut de Physique Nucleaire, IN2P3-CNRS, 69 (France); Lanzalone, G. [Catania Univ., INFN, Laboratori Nazionali del Sud and Dipartimento di Fisica e Astronomia, (Italy); Politi, G. [Catania Univ., INFN, Sezione di Catania and Dipartimento di Fisica e Astronomia (Italy); Rosato, E. [Napoli, Univ., Dipt. di Scienze Fisiche e Sezione INFN (Italy)

    2003-07-01

    For the first time shapes of current pulses from light charged particles and carbon ions are presented. Capabilities for pulse shape discrimination techniques are demonstrated. In this work, charge and current-sensitive preamplifier prototypes for nuclear structure and dynamics experiments have been developed and tested with the aim of improving PSD (pulse shape discrimination) method by studying in detail current signal shapes from particles and ions over a large energy range. Note that current signal shapes have been recently used in atomic cluster studies to identify partitions of carbon cluster fragmentation. The paper is organized as follows. Section 2 is devoted to characterization of preamplifiers. In section 3, results of on beam tests will be presented, discussed and compared to a simple simulation.

  6. Contribution to the study of position sensitive detectors with high spatial resolution for thermal neutron detection

    International Nuclear Information System (INIS)

    Idrissi Fakhr-Eddine, Abdellah.

    1978-01-01

    With a view to improving the spatial resolution of the localization of thermal neutrons, the work covers four position sensitive detectors: - 800 cell multi-detectors (1 dimension), - linear 'Jeu de Jacquet' detectors (1 dimension) - Multi-detector XYP 128x128 (2 dimensions), - 'Jeu de Jacquet' detector with 2 dimensions. Mention is made of the various position finding methods known so far, as well as the reasons for selecting BF 3 as detector gas. A study is then made of the parameters of the multiwire chamber whose principle will form the basis of most of the position detecting appliances subsequently dealt with. Finally, a description is given of the detection tests of the thermal neutrons in the multiwire chamber depending on the pressure, a parameter that greatly affects the accuracy of the position finding. The single dimension position tests on two kinds of appliance, the 800 cell multi-detector for the wide angle diffraction studies, and the linear 'Jeu de Jacquet' detector designed for small angle diffraction are mentioned. A description is then given of two position appliances with two dimensions; the multi-detector XYP 128x128 and the two dimensional 'Jeu de Jacquet' detector. In the case of this latter detector, only the hoped for characteristics are indicated [fr

  7. The position dependent influence that sensitivity correction processing gives the signal-to-noise ratio measurement in parallel imaging

    International Nuclear Information System (INIS)

    Murakami, Koichi; Yoshida, Koji; Yanagimoto, Shinichi

    2012-01-01

    We studied the position dependent influence that sensitivity correction processing gave the signal-to-noise ratio (SNR) measurement of parallel imaging (PI). Sensitivity correction processing that referred to the sensitivity distribution of the body coil improved regional uniformity more than the sensitivity uniformity correction filter with a fixed correction factor. In addition, the position dependent influence to give the SNR measurement in PI was different from the sensitivity correction processing. Therefore, if we divide SNR of the sensitivity correction processing image by SNR of the original image in each pixel and calculate SNR ratio, we can show the position dependent influence that sensitivity correction processing gives the SNR measurement in PI. It is with an index of the sensitivity correction processing precision. (author)

  8. Improvements to a neutral radiation detection and position sensitive process and devices

    International Nuclear Information System (INIS)

    Charpak, Georges; Nguyen, N.H.; Policarpo, Armando.

    1977-01-01

    This invention aims to provide a neutral radiation position sensitive process and device providing a spatial radiation satisfactory for most medical applications and an energy radiation that cannot be reached by gas detectors based on proportional counters or by scintillation counters. Only solid state detectors can compete with respect to energy resolution. The detector described enables large areas to be covered which cannot be reached at accessible costs by solid state detectors. With this aim in view, the invention suggests an incident neutral radiation and position sensitive process, particularly soft gamma and X radiations, whereby photoelectrons are made to form by incident radiation action on gas atoms contained in an enclosure. By means of an electric field, the electrons are diverted towards a space undergoing an electric field high enough in value to create photons by exciting gas atoms and returning them to the de-excited state. The photons are collected, through a transparent window, on a layer of a material for converting such photons into scintillations in the near or visible UV spectrum and the barycentre of the scintillations is positioned on the layer, for instance by photomultipliers or ionization detectors. According to another aspect of the invention, it suggests a detection and position sensitive device comprising (generally downstream of a collimator with a grid of inlet holes) a leak tight containment fitted with an inlet window transparent to incident radiations, filled with a gas producing electrons by interaction with the incident radiation, and fitted with electrodes for generating an electric field to divert the electrons to a space for creating secondary photons [fr

  9. Sensitivity, Specificity, and Positivity Predictors of the Pneumococcal Urinary Antigen Test in Community-Acquired Pneumonia.

    Science.gov (United States)

    Molinos, Luis; Zalacain, Rafael; Menéndez, Rosario; Reyes, Soledad; Capelastegui, Alberto; Cillóniz, Catia; Rajas, Olga; Borderías, Luis; Martín-Villasclaras, Juan J; Bello, Salvador; Alfageme, Inmaculada; Rodríguez de Castro, Felipe; Rello, Jordi; Ruiz-Manzano, Juan; Gabarrús, Albert; Musher, Daniel M; Torres, Antoni

    2015-10-01

    Detection of the C-polysaccharide of Streptococcus pneumoniae in urine by an immune-chromatographic test is increasingly used to evaluate patients with community-acquired pneumonia. We assessed the sensitivity and specificity of this test in the largest series of cases to date and used logistic regression models to determine predictors of positivity in patients hospitalized with community-acquired pneumonia. We performed a multicenter, prospective, observational study of 4,374 patients hospitalized with community-acquired pneumonia. The urinary antigen test was done in 3,874 cases. Pneumococcal infection was diagnosed in 916 cases (21%); 653 (71%) of these cases were diagnosed exclusively by the urinary antigen test. Sensitivity and specificity were 60 and 99.7%, respectively. Predictors of urinary antigen positivity were female sex; heart rate≥125 bpm, systolic blood pressureantibiotic treatment; pleuritic chest pain; chills; pleural effusion; and blood urea nitrogen≥30 mg/dl. With at least six of all these predictors present, the probability of positivity was 52%. With only one factor present, the probability was only 12%. The urinary antigen test is a method with good sensitivity and excellent specificity in diagnosing pneumococcal pneumonia, and its use greatly increased the recognition of community-acquired pneumonia due to S. pneumoniae. With a specificity of 99.7%, this test could be used to direct simplified antibiotic therapy, thereby avoiding excess costs and risk for bacterial resistance that result from broad-spectrum antibiotics. We also identified predictors of positivity that could increase suspicion for pneumococcal infection or avoid the unnecessary use of this test.

  10. Novel single-cell mega-size chambers for electrochemical etching of panorama position-sensitive polycarbonate ion image detectors

    Science.gov (United States)

    Sohrabi, Mehdi

    2017-11-01

    A novel development is made here by inventing panorama single-cell mega-size electrochemical etching (MS-ECE) chamber systems for processing panorama position-sensitive mega-size polycarbonate ion image detectors (MS-PCIDs) of potential for many neutron and ion detection applications in particular hydrogen ions or proton tracks and images detected for the first time in polycarbonates in this study. The MS-PCID is simply a large polycarbonate sheet of a desired size. The single-cell MS-ECE invented consists of two large equally sized transparent Plexiglas sheets as chamber walls holding a MS-PCID and the ECE chamber components tightly together. One wall has a large flat stainless steel electrode (dry cell) attached to it which is directly in contact with the MS-PCID and the other wall has a rod electrode with two holes to facilitate feeding and draining out the etching solution from the wet cell. A silicon rubber washer plays the role of the wet cell to hold the etchant and the electrical insulator to isolate the dry cell from the wet cell. A simple 50 Hz-HV home-made generator provides an adequate field strength through the two electrodes across the MS-ECE chamber. Two panorama single-cell MS-ECE chamber systems (circular and rectangular shapes) constructed were efficiently applied to processing the MS-PCIDs for 4π ion emission image detection of different gases in particular hydrogen ions or protons in a 3.5 kJ plasma focus device (PFD as uniquely observed by the unaided eyes). The panorama MS-PCID/MS-ECE image detection systems invented are novel with high potential for many applications in particular as applied to 4π panorama ion emission angular distribution image detection studies in PFD space, some results of which are presented and discussed.

  11. A rotation-symmetric, position-sensitive annular detector for maximum counting rates

    International Nuclear Information System (INIS)

    Igel, S.

    1993-12-01

    The Germanium Wall is a semiconductor detector system containing up to four annular position sensitive ΔE-detectors from high purity germanium (HPGe) planned to complement the BIG KARL spectrometer in COSY experiments. The first diode of the system, the Quirl-detector, has a two dimensional position sensitive structure defined by 200 Archimedes' spirals on each side with opposite orientation. In this way about 40000 pixels are defined. Since each spiral element detects almost the same number of events in an experiment the whole system can be optimized for maximal counting rates. This paper describes a test setup for a first prototype of the Quirl-detector and the results of test measurements with an α-source. The detector current and the electrical separation of the spiral elements were measured. The splitting of signals due to the spread of charge carriers produced by an incident ionizing particle on several adjacent elements was investigated in detail and found to be twice as high as expected from calculations. Its influence on energy and position resolution is discussed. Electronic crosstalk via signal wires and the influence of noise from the magnetic spectrometer has been tested under experimental conditions. Additionally, vacuum feedthroughs based on printed Kapton foils pressed between Viton seals were fabricated and tested successfully concerning their vacuum and thermal properties. (orig.)

  12. A large, high performance, curved 2D position-sensitive neutron detector

    CERN Document Server

    Fried, J W; Mahler, G J; Makowiecki, D S; Mead, J A; Radeka, V; Schaknowski, N A; Smith, G C; Yu, B

    2002-01-01

    A new position-sensitive neutron detector has been designed and constructed for a protein crystallography station at LANL's pulsed neutron source. This station will be one of the most advanced instruments at a major neutron user facility for protein crystallography, fiber and membrane diffraction. The detector, based on neutron absorption in sup 3 He, has a large sensitive area of 3000 cm sup 2 , angular coverage of 120 deg. , timing resolution of 1 mu s, rate capability in excess of 10 sup 6 s sup - sup 1 , position resolution of about 1.5 mm FWHM, and efficiency >50% for neutrons of interest in the range 1-10 A. Features that are key to these remarkable specifications are the utilization of eight independently operating segments within a single gas volume, fabrication of the detector vessel and internal segments with a radius of curvature of about 70 cm, optimized position readout based on charge division and signal shaping with gated baseline restoration, and engineering design with high-strength aluminum ...

  13. Application of digital waveform processing to position-sensitive proportional counter

    International Nuclear Information System (INIS)

    Takenaka, Yasuto; Uritani, Akira; Mori, Chizuo

    1995-01-01

    In a charge-division type position-sensitive proportional counter (PSPC) with an anode wire of small resistance, a reflected component from an opposite end and thermal noise involved in signals deteriorate the position resolution of the PSPC. A digital waveform processing method was applied to the reduction of these undesirable effects by skillfully utilizing their signal characteristics that can be observed as inversely correlative signals between two-output signals from both sides of the PSPC. The digital waveform processing could improve the position resolution compared to a conventional pulse height processing method with analog filters. When the digital waveform processing was applied to signals of an equivalent circuit simulating the PSPC, the position resolutions defined by the full width at half maximum were improved to about 30% of those of conventional analog pulse processing. In the case of an actual PSPC, the position resolutions by the digital waveform processing were improved by 4-10% as compared with those of conventional pulse height processing. (author)

  14. A pulse stacking method of particle counting applied to position sensitive detection

    International Nuclear Information System (INIS)

    Basilier, E.

    1976-03-01

    A position sensitive particle counting system is described. A cyclic readout imaging device serves as an intermediate information buffer. Pulses are allowed to stack in the imager at very high counting rates. Imager noise is completely discriminated to provide very wide dynamic range. The system has been applied to a detector using cascaded microchannel plates. Pulse height spread produced by the plates causes some loss of information. The loss is comparable to the input loss of the plates. The improvement in maximum counting rate is several hundred times over previous systems that do not permit pulse stacking. (Auth.)

  15. A time resolving data acquisition system for multiple high-resolution position sensitive detectors

    International Nuclear Information System (INIS)

    Dimmler, D.G.

    1988-01-01

    An advanced time resolving data collection system for use in neutron and x-ray spectrometry has been implemented and put into routine operation. The system collects data from high-resolution position-sensitive area detectors with a maximum cumulative rate of 10/sup 6/ events per second. The events are sorted, in real-time, into many time-slice arrays. A programmable timing control unit allows for a wide choice of time sequences and time-slice array sizes. The shortest dwell time on a slice may be below 1 ms and the delay to switch between slices is zero

  16. The performance of prototype position-sensitive neutron detectors on SXD at ISIS

    International Nuclear Information System (INIS)

    Wilson, C.C.

    1989-02-01

    The performance of two position-sensitive neutron detector designed for use on the single crystal diffractometer (SXD) at ISIS is assessed. The two detectors examined were the Anger camera 6 Li-glass scintillator PSD and a prototype fibre-optic encoded PSD based on 6 Li-doped ZnS plastic scintillator. The latter detector is found to be both simpler to fabricate and to produce better results on the evidence to date. A summary of some of the expected science from SXD and the performance of the detectors with respect to this is also given. (author)

  17. Ultrafast readout of scintillating fibers using upgraded position-sensitive photomultipliers

    International Nuclear Information System (INIS)

    Onel, Y.

    1994-01-01

    Experimental results obtained with commercially available position-sensitive photomultipliers (PSPM) coupled with 0.5 mm diameter scintillating fiber arrays show some promising performances such as space resolution better than 200 μm and time resolution ∼ 1.5 ns with a detection efficiency higher than 90%. Major progress has also been recently achieved with an upgrade of a PSPM based on new grid dynode structures. Two-track spatial resolution has been studied using the upgraded PSPM. Initial studies demonstrate that two tracks separated by a minimum distance of 3 mm are resolved

  18. Measurement and analysis of field-induced crystallographic texture using curved position-sensitive diffraction detectors

    DEFF Research Database (Denmark)

    Simons, Hugh; Daniels, John E.; Studer, Andrew J.

    2014-01-01

    This paper outlines measurement and analysis methodologies created for determining the structural responses of electroceramics to an electric field. A sample stage is developed to apply electric fields to ceramic materials at elevated temperatures during neutron diffraction experiments. The tested...... employing a curved positive sensitive detector. Methodologies are proposed to account for the geometrical effects when vector fields are applied to textured materials with angularly dispersive detector geometries. Representative results are presented for the ferroelectric (Bi1/2Na1/2)TiO3-6%BaTiO3 (BNT-6BT...

  19. A new position-sensitive transmission detector for epithermal neutron imaging

    International Nuclear Information System (INIS)

    Schooneveld, E M; Kockelmann, W; Rhodes, N; Tardocchi, M; Gorini, G; Perelli Cippo, E; Nakamura, T; Postma, H; Schillebeeckx, P

    2009-01-01

    A new neutron resonant transmission (NRT) detector for epithermal neutron imaging has been designed and built for the ANCIENT CHARM project, which is developing a set of complementary neutron imaging methods for analysis of cultural heritage objects. One of the techniques being exploited is NRT with the aim of performing bulk elemental analysis. The 16-pixel prototype NRT detector consists of independent crystals of 2 x 2 mm pixel size, which allow for 2D position-sensitive transmission measurements with epithermal neutrons. First results obtained at the ISIS pulsed spallation neutron source are presented. (fast track communication)

  20. Conceptual design of elliptical cavities for intensity and position sensitive beam measurements in storage rings

    International Nuclear Information System (INIS)

    Sanjari, M S; Chen, X; Hülsmann, P; Litvinov, Yu A; Nolden, F; Piotrowski, J; Steck, M; Stöhlker, Th

    2015-01-01

    Position sensitive beam monitors are indispensable for the beam diagnostics in storage rings. Apart from their applications in the measurements of beam parameters, they can be used in non-destructive in-ring decay studies of radioactive ion beams as well as enhancing precision in the isochronous mass measurement technique. In this work, we introduce a novel approach based on cavities with elliptical cross-section, in order to compensate the limitations of known designs for the application in ion storage rings. The design is aimed primarily for future heavy ion storage rings of the FAIR project. The conceptual design is discussed together with simulation results. (paper)

  1. Identifying Moderators of the Link Between Parent and Child Anxiety Sensitivity: The Roles of Gender, Positive Parenting, and Corporal Punishment.

    Science.gov (United States)

    Graham, Rebecca A; Weems, Carl F

    2015-07-01

    A substantial body of literature suggests that anxiety sensitivity is a risk factor for the development of anxiety problems and research has now begun to examine the links between parenting, parent anxiety sensitivity and their child's anxiety sensitivity. However, the extant literature has provided mixed findings as to whether parent anxiety sensitivity is associated with child anxiety sensitivity, with some evidence suggesting that other factors may influence the association. Theoretically, specific parenting behaviors may be important to the development of child anxiety sensitivity and also in understanding the association between parent and child anxiety sensitivity. In this study, 191 families (n = 255 children and adolescents aged 6-17 and their parents) completed measures of child anxiety sensitivity (CASI) and parenting (APQ-C), and parents completed measures of their own anxiety sensitivity (ASI) and their parenting (APQ-P). Corporal punishment was associated with child anxiety sensitivity and the child's report of their parent's positive parenting behaviors moderated the association between parent and child anxiety sensitivity. The child's gender was also found to moderate the association between parent and child anxiety sensitivity, such that there was a positive association between girls' and their parents anxiety sensitivity and a negative association in boys. The findings advance the understanding of child anxiety sensitivity by establishing a link with corporal punishment and by showing that the association between parent and child anxiety sensitivity may depend upon the parenting context and child's gender.

  2. A two-dimensional position sensitive gas chamber with scanned charge transfer readout

    International Nuclear Information System (INIS)

    Gomez, F.; Iglesias, A.; Lobato, R.; Mosquera, J.; Pardo, J.; Pena, J.; Pazos, A.; Pombar, M.; Rodriguez, A.

    2003-01-01

    We have constructed and tested a two-dimensional position sensitive parallel-plate gas ionization chamber with scanned charge transfer readout. The scan readout method described here is based on the development of a new position-dependent charge transfer technique. It has been implemented by using gate strips perpendicularly oriented to the collector strips. This solution reduces considerably the number of electronic readout channels needed to cover large detector areas. The use of a 25 μm thick kapton etched circuit allows high charge transfer efficiency with a low gating voltage, consequently needing a very simple commutating circuit. The present prototype covers 8x8 cm 2 with a pixel size of 1.27x1.27 mm 2 . Depending on the intended use and beam characteristics a smaller effective pixel is feasible and larger active areas are possible. This detector can be used for X-ray or other continuous beam intensity profile monitoring

  3. Investigation of the pulse shape analysis for the position sensitive γ-ray spectrometer AGATA

    Energy Technology Data Exchange (ETDEWEB)

    Lewandowski, Lars; Birkenbach, Benedikt; Reiter, Peter [Institut fuer Kernphysik Koeln (Germany); Collaboration: AGATA-Collaboration

    2015-07-01

    The next generation of γ-ray spectrometers like AGATA will provide high quality γ-ray spectra by the new Gamma-Ray Tracking technique (GRT). Position sensitive HPGe detectors will allow for precise Doppler correction and small broadening of lines for spectroscopy at relativistic energies. GRT is based on the interaction position of the γ-rays within the volume of the highly segmented germanium detectors provided by Pulse Shape Analysis (PSA) methods. The proof of principle of GRT was already demonstrated with great success however systematic deviations from expected results occur. The parameterization of the following detector properties and their impact on PSA were thoroughly investigated and optimized: electron and hole mobility, crystal axis orientation, space charge distributions, crystal impurities, response functions of preamplifiers and digitizers, linear and differential crosstalk, time alignment of pulses and the distance metric. Results of an improved PSA performance are presented.

  4. Penicillin sensitivity among children without a positive history for penicillin allergy.

    Science.gov (United States)

    Cetinkaya, Feyzullah; Cag, Yakup

    2004-06-01

    To establish the prevalence of positive penicillin skin tests among outpatients without any drug reaction history. Skin testing was performed in 147 children (aged 6-13 years) who had had received a penicillin preparation at least three times in the last 12 months without any allergic reaction. Before testing, detailed pediatric and allergy history were learned and then all children were tested with benzyl penicilloyl polylysin (PPL) and mixture of minor antigenic determinants. The test procedures were made epidermally and intradermally subsequently in every subject. The overall frequency of positive skin reactions to penicillin antigens was 10.2%. A mild systemic reaction was observed in one of the children during testing with PPL. We concluded that frequent use of penicillin and other beta-lactam antibiotics leads to sensitization of children in our study population despite these children seem to be asymptomatic during testing time. Copyright 2004 Blackwell Munksgaard

  5. Derivation of the point spread function for zero-crossing-demodulated position-sensitive detectors

    International Nuclear Information System (INIS)

    Nowlin, C.H.

    1976-07-01

    This work is a mathematical derivation of a high-quality approximation to the point spread function for position-sensitive detectors (PSDs) that use pulse-shape modulation and crossover-time demodulation. The approximation is determined as a general function of the input signals to the crossover detectors so as to enable later determination of optimum position-decoding filters for PSDs. This work is precisely applicable to PSDs that use either RC or LC transmission line encoders. The effects of random variables, such as charge collection time, in the encoding process are included. In addition, this work presents a new, rigorous method for the determination of upper and lower bounds for conditional crossover-time distribution functions (closely related to first-passage-time distribution functions) for arbitrary signals and arbitrary noise covariance functions

  6. Instrumentation for Position Sensitive Detector-Powder diffractometer at CENM-Maamora

    International Nuclear Information System (INIS)

    Messous, M.-Y.; Belhorma, B.; Labrim, H.; El-Bakkari, B.; Jabri, H.

    2013-06-01

    Linear position sensitive detectors are widely used to configure neutron diffractometer and other instruments. Necessary front-end electronics and data acquisition system was developed to fulfil such instruments built around the research reactor. In this paper, the front-end electronics dedicated to the neutron powder diffractometer which will be installed in the axial beam port of the Triga Mark II research reactor (Center of Nuclear Studies of Maamora) is described. It consists of High voltage power supply, a Position-decoder and a Multichannel analyzer and data acquisition software. The 3 He-PSD detector response exposed to the neutron flow emitted by 252 Cf source held in paraffin spheres with distinct thicknesses for moderation effect, is shown. Monte-Carlo N Particles code (MCNP) simulations were also performed to study both the detector performance and the paraffin efficiency. (authors)

  7. First results from Position-Sensitive quantum calorimeters using Mo/Au Transition-Edge Sensors

    International Nuclear Information System (INIS)

    Figueroa-Feliciano, Enectali; Chervenak, Jay; Finkbeiner, Fred M.; Li, Mary; Lindeman, Mark A.; Stahle, Caroline K.; Stahle, Carl M.

    2002-01-01

    We report the first results from a high-energy-resolution imaging spectrometer called a Position-Sensitive Transition-Edge Sensor (PoST). A PoST is a quantum calorimeter consisting of two Transition Edge Sensors (TESs) on the ends of a long absorber to do one dimensional imaging spectroscopy. Comparing rise time and energy information, the position of the event in the PoST is determined. Energy is inferred from the sum of the two pulses. We have fabricated 7- and 15-pixel PoSTs using Mo-Au TESs and Au absorbers. We have achieved 32 eV FWHM energy resolution at 1.5 keV with a 7-pixel PoST calorimeter

  8. Characterization of Sensitivity Encoded Silicon Photomultiplier (SeSP) with 1-Dimensional and 2-Dimensional Encoding for High Resolution PET/MR

    Science.gov (United States)

    Omidvari, Negar; Schulz, Volkmar

    2015-06-01

    This paper evaluates the performance of a new type of PET detectors called sensitivity encoded silicon photomultiplier (SeSP), which allows a direct coupling of small-pitch crystal arrays to the detector with a reduction in the number of readout channels. Four SeSP devices with two separate encoding schemes of 1D and 2D were investigated in this study. Furthermore, both encoding schemes were manufactured in two different sizes of 4 ×4 mm2 and 7. 73 ×7. 9 mm2, in order to investigate the effect of size on detector parameters. All devices were coupled to LYSO crystal arrays with 1 mm pitch size and 10 mm height, with optical isolation between crystals. The characterization was done for the key parameters of crystal-identification, energy resolution, and time resolution as a function of triggering threshold and over-voltage (OV). Position information was archived using the center of gravity (CoG) algorithm and a least squares approach (LSQA) in combination with a mean light matrix around the photo-peak. The positioning results proved the capability of all four SeSP devices in precisely identifying all crystals coupled to the sensors. Energy resolution was measured at different bias voltages, varying from 12% to 18% (FWHM) and paired coincidence time resolution (pCTR) of 384 ps to 1.1 ns was obtained for different SeSP devices at about 18 °C room temperature. However, the best time resolution was achieved at the highest over-voltage, resulting in a noise ratio of 99.08%.

  9. A broadband-sensitive upconverter La(Ga0.5Sc0.5)O3:Er,Ni,Nb for crystalline silicon solar cells

    International Nuclear Information System (INIS)

    Takeda, Yasuhiko; Mizuno, Shintaro; Luitel, Hom Nath; Tani, Toshihiko

    2016-01-01

    We have developed an upconverter that significantly broadens the sensitive range, to overcome the shortcoming that conventional Er 3+ -doped upconverters used for crystalline silicon solar cells can utilize only a small portion of the solar spectrum at around 1.55 μm. We have designed the combination of the sensitizers and host material to utilize photons not absorbed by silicon or Er 3+ ions. Ni 2+ ions have been selected as the sensitizers that absorb photons in the wavelength range between the silicon absorption edge (1.1 μm) and the Er 3+ absorption band and transfer the energies to the Er 3+ emitters, with La(Ga,Sc)O 3 as the host material. The Ga to Sc ratio has been optimized to tune the location of the Ni 2+ absorption band for sufficient energy transfer. Co-doping with Nb 5+ ions is needed for charge balance to introduce divalent Ni 2+ ions into the trivalent Ga 3+ and Sc 3+ sites. In addition to 1.45–1.58 μm photons directly absorbed by the Er 3+ ions, we have demonstrated upconversion of 1.1–1.35 μm photons in the Ni 2+ absorption band to 0.98 μm photons, using 10% Er, 0.5% Ni, and 0.5% Nb-doped La(Ga 0.5 Sc 0.5 )O 3 . The broadband-sensitive upconverter developed here can improve conversion efficiency of crystalline silicon solar cells more notably than conventional ones

  10. Integrated X-ray and charged particle active pixel CMOS sensor arrays using an epitaxial silicon sensitive region

    International Nuclear Information System (INIS)

    Kleinfelder, Stuart; Bichsel, Hans; Bieser, Fred; Matis, Howard S.; Rai, Gulshan; Retiere, Fabrice; Weiman, Howard; Yamamoto, Eugene

    2002-01-01

    Integrated CMOS Active Pixel Sensor (APS) arrays have been fabricated and tested using X-ray and electron sources. The 128 by 128 pixel arrays, designed in a standard 0.25 micron process, use a ∼10 micron epitaxial silicon layer as a deep detection region. The epitaxial layer has a much greater thickness than the surface features used by standard CMOS APS, leading to stronger signals and potentially better signal-to-noise ratio (SNR). On the other hand, minority carriers confined within the epitaxial region may diffuse to neighboring pixels, blur images and reduce peak signal intensity. But for low-rate, sparse-event images, centroid analysis of this diffusion may be used to increase position resolution. Careful trade-offs involving pixel size and sense-node area verses capacitance must be made to optimize overall performance. The prototype sensor arrays, therefore, include a range of different pixel designs, including different APS circuits and a range of different epitaxial layer contact structures. The fabricated arrays were tested with 1.5 GeV electrons and Fe-55 X-ray sources, yielding a measured noise of 13 electrons RMS and an SNR for single Fe-55 X-rays of greater than 38

  11. Positive alcohol use expectancies moderate the association between anxiety sensitivity and alcohol use across adolescence.

    Science.gov (United States)

    Borges, Allison M; Lejuez, Carl W; Felton, Julia W

    2018-06-01

    Anxiety sensitivity (AS), or the fear of anxious symptoms and the belief that these symptoms may have negative physical, social, and cognitive consequences, is one personality trait that emerges in early adolescence and may be linked to alcohol use. However, findings are equivocal as to whether elevated AS during adolescence directly predicts alcohol use. Adolescents do report increases in positive alcohol use expectancies during this developmental period, and these expectancies have been found to be significantly associated with alcohol use. The current study examined whether positive alcohol use expectancies and AS in early adolescence predicted changes in alcohol use throughout adolescence. This aim was examined via secondary data analyses from a longitudinal study examining the development of risk behaviors in adolescents. Results of univariate latent growth curve modeling suggest that AS alone was not a significant predictor of baseline alcohol use or change in use over time after controlling for gender, age, and self-reported anxiety. However, AS in early adolescence was found to be a significant predictor of increases in alcohol use across adolescence for youth who reported greater positive alcohol use expectancies. These results indicate that beliefs regarding the positive effects of alcohol use are an important moderator in the relation between AS and change in alcohol use during adolescence. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Serial position effects are sensitive predictors of conversion from MCI to Alzheimer's disease dementia.

    Science.gov (United States)

    Egli, Simone C; Beck, Irene R; Berres, Manfred; Foldi, Nancy S; Monsch, Andreas U; Sollberger, Marc

    2014-10-01

    It is unclear whether the predictive strength of established cognitive variables for progression to Alzheimer's disease (AD) dementia from mild cognitive impairment (MCI) varies depending on time to conversion. We investigated which cognitive variables were best predictors, and which of these variables remained predictive for patients with longer times to conversion. Seventy-five participants with MCI were assessed on measures of learning, memory, language, and executive function. Relative predictive strengths of these measures were analyzed using Cox regression models. Measures of word-list position-namely, serial position scores-together with Short Delay Free Recall of word-list learning best predicted conversion to AD dementia. However, only serial position scores predicted those participants with longer time to conversion. Results emphasize that the predictive strength of cognitive variables varies depending on time to conversion to dementia. Moreover, finer measures of learning captured by serial position scores were the most sensitive predictors of AD dementia. Copyright © 2014 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

  13. Development of a position-sensitive fission counter and measurement of neutron flux distributions

    International Nuclear Information System (INIS)

    Yamagishi, Hideshi; Soyama, Kazuhiko; Kakuta, Tsunemi

    2001-08-01

    A position-sensitive fission counter (PSFC) that operates in high neutron flux and high gamma-ray background such as at the side of a power reactor vessel has been developed. Neutron detection using the PSFC with a solenoid electrode is based on a delay-line method. The PSFC that has the outer diameter of 25 mm and the sensitive length of 1000 mm was manufactured for investigation of the performances. The PSFC provided output current pulses that were sufficiently higher than the alpha noise, though the PSFC has a solenoid electrode and large electrode-capacitance. The S/N ratio of PSFC outputs proved to be higher than that of ordinary fission counters with 200 mm sensitive length. A performance test to measure neutron flux distributions by a neutron measuring system with the PSFC was carried out by the side of a graphite pile, W2.4 x H1.4 x L1.2 m, with neutron sources, Am-Be 370 GBq x 2. It was confirmed that the neutron flux distribution was well measured with the system. (author)

  14. Sensitivity and offset calibration for the beam position monitors at the Advanced Photon Source

    International Nuclear Information System (INIS)

    Chung, Y.; Barr, D.; Decker, G.; Evans, K. Jr.; Kahana, E.

    1995-01-01

    The beam position monitors (BPMs) play a critically important role in commissioning and operation of accelerators. Accurate determination of the offsets relative to the magnetic axis and sensitivities of individual BPMs is thus needed. We will describe in this paper the schemes for calibrating all of the 360 BPMs for sensitivity and offset in the 7-GeV Advanced Photon Source (APS) storage ring and the results. For the sensitivity calibration, a 2-dimensional map of the BPM response in the aluminum vacuum chamber is obtained theoretically, which is combined with the measured nonlinear response of the BPM electronics. A set of 2-dimensional polynomial coefficients is then obtained to approximate the result analytically. The offset calibration of the BPMs is done relative to the magnetic axis of the quadrupoles using the beam. This avoids the problem arising from various mechanical sources as well as the offset in the processing electronics. The measurement results for the resolution and long-term drift of the BPM electronics shows 0.06-μm/√Hz resolution and 2-μm/hr drift over a period of 1.5 hrs

  15. Development of a geometric uncertainty model describing the accuracy of position-sensitive, coincidence neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Trivelpiece, Cory L., E-mail: cory@psu.ed [Department of Mechanical and Nuclear Engineering, The Pennsylvania, State University, University Park, PA 16802 (United States); Brenizer, J.S. [Department of Mechanical and Nuclear Engineering, The Pennsylvania, State University, University Park, PA 16802 (United States)

    2011-01-01

    A diameter of uncertainty (D{sub u}) was derived from a geometric uncertainty model describing the error that would be introduced into position-sensitive, coincidence neutron detection measurements by charged-particle transport phenomena and experimental setup. The transport of {alpha} and Li ions, produced by the {sup 10}B(n,{alpha}) {sup 7}Li reaction, through free-standing boro-phosphosilicate glass (BPSG) films was modeled using the Monte Carlo code SRIM, and the results of these simulations were used as input to determine D{sub u} for position-sensitive, coincidence techniques. The results of these calculations showed that D{sub u} is dependent on encoder separation, the angle of charged particle emission, and film thickness. For certain emission scenarios, the magnitude of D{sub u} is larger than the physical size of the neutron converting media that were being modeled. Spheres of uncertainty were developed that describe the difference in flight path times among the bounding-case emission scenarios that were considered in this work. It was shown the overlapping spheres represent emission angles and particle flight path lengths that would be difficult to resolve in terms of particle time-of-flight measurements. However, based on the timing resolution of current nuclear instrumentation, emission events that yield large D{sub u} can be discriminated by logical arguments during spectral deconvolution.

  16. Position-sensitive radiation monitoring (surface contamination monitor). Innovative technology summary report

    International Nuclear Information System (INIS)

    1999-06-01

    The Shonka Research Associates, Inc. Position-Sensitive Radiation Monitor both detects surface radiation and prepares electronic survey map/survey report of surveyed area automatically. The electronically recorded map can be downloaded to a personal computer for review and a map/report can be generated for inclusion in work packages. Switching from beta-gamma detection to alpha detection is relatively simple and entails moving a switch position to alpha and adjusting the voltage level to an alpha detection level. No field calibration is required when switching from beta-gamma to alpha detection. The system can be used for free-release surveys because it meets the federal detection level sensitivity limits requires for surface survey instrumentation. This technology is superior to traditionally-used floor contamination monitor (FCM) and hand-held survey instrumentation because it can precisely register locations of radioactivity and accurately correlate contamination levels to specific locations. Additionally, it can collect and store continuous radiological data in database format, which can be used to produce real-time imagery as well as automated graphics of survey data. Its flexible design can accommodate a variety of detectors. The cost of the innovative technology is 13% to 57% lower than traditional methods. This technology is suited for radiological surveys of flat surfaces at US Department of Energy (DOE) nuclear facility decontamination and decommissioning (D and D) sites or similar public or commercial sites

  17. Position-sensitive radiation monitoring (surface contamination monitor). Innovative technology summary report

    Energy Technology Data Exchange (ETDEWEB)

    1999-06-01

    The Shonka Research Associates, Inc. Position-Sensitive Radiation Monitor both detects surface radiation and prepares electronic survey map/survey report of surveyed area automatically. The electronically recorded map can be downloaded to a personal computer for review and a map/report can be generated for inclusion in work packages. Switching from beta-gamma detection to alpha detection is relatively simple and entails moving a switch position to alpha and adjusting the voltage level to an alpha detection level. No field calibration is required when switching from beta-gamma to alpha detection. The system can be used for free-release surveys because it meets the federal detection level sensitivity limits requires for surface survey instrumentation. This technology is superior to traditionally-used floor contamination monitor (FCM) and hand-held survey instrumentation because it can precisely register locations of radioactivity and accurately correlate contamination levels to specific locations. Additionally, it can collect and store continuous radiological data in database format, which can be used to produce real-time imagery as well as automated graphics of survey data. Its flexible design can accommodate a variety of detectors. The cost of the innovative technology is 13% to 57% lower than traditional methods. This technology is suited for radiological surveys of flat surfaces at US Department of Energy (DOE) nuclear facility decontamination and decommissioning (D and D) sites or similar public or commercial sites.

  18. Ultrafast readout of scintillating fibres using upgraded position-sensitive photomultipliers

    CERN Document Server

    Agoritsas, V; Ditta, J; Dufournaud, J; Giacomich, R; Gorin, A M; Kuroda, K; Meshchanin, A P; Newsom, C R; Nurushev, S B; Önel, Y M; Okada, K; Oshima, N; Pauletta, G; Penzo, Aldo L; Rakhmatov, V E; Rykalin, V I; Salvato, G; Schiavon, R P; Sillou, D; Solovyanov, V L; Takeutchi, F; Vasilev, V; Vasilchenko, V G; Villari, A C C; Yamada, R; Yoshida, T; CERN. Geneva. Detector Research and Development Committee

    1991-01-01

    In view of the new possibilities for event detection and tracking in future multi-TeV collider experiments, we propose to improve the performance of position-sensitive photomultipliers and, with it, to realize an ultrafast readout device of scintillating fibres; this should play a unique role in the complex of a future vertex detector, owing to its inherent subnanosecond resolving time as well as its capability of an extremely high counting rate. Our proposal is first aimed at upgrading the position-sensitive PM, in particular its space and time resolutions. Full advantage of the new phototube will be demonstrated in its immediate application to a generic prototype of a scintillating-fibre detector. Our programme also includes intensive R&D on a real-time digitization of the multihit topology, which should provide an essential back-up to the vertex tracking at extremely high rates, one of the most difficult problems relevant to the expected high performance of the LHC.

  19. Sensitivity and specificity of oral HPV detection for HPV-positive head and neck cancer.

    Science.gov (United States)

    Gipson, Brooke J; Robbins, Hilary A; Fakhry, Carole; D'Souza, Gypsyamber

    2018-02-01

    The incidence of HPV-related head and neck squamous cell carcinoma (HPV-HNSCC) is increasing. Oral samples are easy and non-invasive to collect, but the diagnostic accuracy of oral HPV detection methods for classifying HPV-positive HNSCC tumors has not been well explored. In a systematic review, we identified eight studies of HNSCC patients meeting our eligibility criteria of having: (1) HPV detection in oral rinse or oral swab samples, (2) tumor HPV or p16 testing, (3) a publication date within the last 10 years (January 2007-May 2017, as laboratory methods change), and (4) at least 15 HNSCC cases. Data were abstracted from each study and a meta-analysis performed to calculate sensitivity and specificity. Eight articles meeting inclusion criteria were identified. Among people diagnosed with HNSCC, oral HPV detection has good specificity (92%, 95% CI = 82-97%) and moderate sensitivity (72%, 95% CI = 45-89%) for HPV-positive HNSCC tumor. Results were similar when restricted to studies with only oropharyngeal cancer cases, with oral rinse samples, or testing for HPV16 DNA (instead of any oncogenic HPV) in the oral samples. Among those who already have HNSCC, oral HPV detection has few false-positives but may miss one-half to one-quarter of HPV-related cases (false-negatives). Given these findings in cancer patients, the utility of oral rinses and swabs as screening tests for HPV-HNSCC among healthy populations is probably limited. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Recent improvements to RC-line encoded position-sensitive proportional counters

    International Nuclear Information System (INIS)

    Borkowski, C.J.; Kopp, M.K.

    1977-01-01

    Continuing research on the principles of position encoding with RC lines has advanced the design of position-sensitive proportional counters (PSPCs) to meet the requirements for high count rates (>10 5 counts/sec) and good spatial resolution (>10 4 spatial elements) in small-angle scattering experiments with x rays and neutrons. Low-noise preamplifiers were developed with pole-zero cancellation in the feedback circuit and modular linear amplifiers with passive RCL shaping which, compared to previous designs, reduce output saturation at high count rates approx.20 times and shorten the position signal processing time to 2 ) for low-energy ( 800 x 800 mm 2 ) for the measurement of small-angle scattering with neutrons. The method of electronic thickness discrimination was applied to change the effective thickness of an area PSPC from 12 to 2 cm whenever the molybdenum target of an x-ray generator was changed to a copper target. This thickness adjustment increased the signal-to-background ratio by a factor of approx.6 for the 8-keV photons from the copper target, while maintaining a >90% detection efficiency

  1. Preliminary Study of Position-Sensitive Large-Area Radiation Portal Monitor

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Chang Hwy; Kim, Hyunok; Moon, Myung Kook [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Jongyul [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Park, Jong Won; Lim, Yong Kon [Korea Institute of Ocean Science and Technology, Daejeon (Korea, Republic of)

    2013-10-15

    An RPM, which is a passive inspection method, is a system for monitoring the movement of radioactive materials at an airport, seaport, border, etc. To detect a γ-ray, an RPM using the plastic scintillator is generally used. The method of γ-ray detection using an RPM with a plastic scintillator is to measure lights generated by an incident γ-ray in the scintillator. Generally, a large-area RPM uses one or two photomultiplier tubes (PMT) for light collection. However, in this study, we developed a 4-ch RPM that can measure the radiation signal using 4 PMTs. The reason for using 4 PMTs is to calculate the position of the radiation source. In addition, we developed an electric device for acquisition of a 4-ch output signal at the same time. To estimate the performance of the developed RPM, we performed an RPM test using a {sup 60}Co γ-ray check source. In this study, we performed the development of a 4-ch RPM. The major function of the typical RPM is to measure the radiation. However, we developed a position-sensitive 4-ch RPM, which can be used to measure the location of the radiation source, as well as the radiation measurement, at the same time. In the future, we plan to develop an algorithm for a position detection of the radiation. In addition, an algorithm will be applied to an RPM.

  2. Installation of the light tight cover for the SSD modules (the modules are behind the aluminium plate). The silicon sensors are sensitive to light tight, so ambient light will increase the noise and may even damage them.

    CERN Multimedia

    Nooren, G.

    2004-01-01

    Installation of the light tight cover for the SSD modules (the modules are behind the aluminium plate). The silicon sensors are sensitive to light tight , so ambient light will increase the noise and may even damage them.

  3. Simulation and optimisation of a position sensitive scintillation detector with wavelength shifting fibers for thermal neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Herzkamp, Matthias; Engels, Ralf; Kemmerling, Guenter [ZEA-2, Forschungszentrum Juelich (Germany); Brueckel, Thomas [JCNS, Forschungszentrum Juelich (Germany); Stahl, Achim [III. Physikalisches Institut B, RWTH Aachen (Germany); Waasen, Stefan van [ZEA-2, Forschungszentrum Juelich (Germany); Faculty of Engineering, University of Duisburg-Essen (Germany)

    2015-07-01

    In neutron scattering experiments it is important to have position sensitive large scale detectors for thermal neutrons. A detector based on a neutron scintillator with wave length shifting fibers is a new kind of such a detector. We present the simulation of the detector based on the microscopic structure of the scintillation material of the mentioned detector. It consists of a converter and a scintillation powder bound in a matrix. The converter in our case is lithium fluoride with enriched lithium 6, to convert thermal neutrons into high energetic alpha and triton particles. The scintillation material is silver doped zinc sulfide. We show that pulse height spectra obtained by these scintillators can be be explained by the simple model of randomly distributed spheres of zinc sulfide and lithium fluoride. With this model, it is possible to optimise the mass ratio of zinc sulfide to lithium fluoride with respect to detection efficiency and/or energy deposition in zinc sulfide.

  4. Environmental gram-positive mastitis treatment: in vitro sensitivity and bacteriologic cure.

    Science.gov (United States)

    Cattell, M B; Dinsmore, R P; Belschner, A P; Carmen, J; Goodell, G

    2001-09-01

    A clinical trial was conducted in a large dairy herd to determine the efficacy of intramammary pirlimycin hydrochloride administration during lactation for bacteriologic clearance of gram-positive environmental clinical and subclinical mastitis infections. Quarters infected with environmental streptococci that received pirlimycin therapy (13/28) were 1.8 times more likely to resolve infection than untreated quarters (5/14). The small numbers of quarters infected with coagulase-negative staphylococci resulted in inadequate power to assess treatment differences in cure rate. Although the association was not statistically significant, quarters from cows with sensitive environmental streptococci isolates from composite samples (8/13) resolved infection with treatment at approximately twice the rate of treated quarters with resistant isolates (3/10).

  5. A large-area, position-sensitive neutron detector with neutron/γ-ray discrimination capabilities

    International Nuclear Information System (INIS)

    Zecher, P.D.; Galonsky, A.; Kruse, J.J.; Gaff, S.J.; Ottarson, J.; Wang, J.; Seres, Z.; Ieki, K.; Iwata, Y.; Schelin, H.

    1997-01-01

    To further study neutron-rich halo nuclei, we have constructed a neutron detector array. The array consists of two separate banks of detectors, each of area 2 x 2 m 2 and containing 250 l of liquid scintillator. Each bank is position-sensitive to better than 10 cm. For neutron time-of-flight measurements, the time resolution of the detector has been demonstrated to be about 1 ns. By using the scintillator NE-213, we are able to distinguish between neutron and γ-ray signals above 1 MeV electron equivalent energy. Although the detector array was constructed for a particular experiment it has also been used in a number of other experiments. (orig.)

  6. Design and development of 1 mm resolution PET detectors with position-sensitive PMTs

    CERN Document Server

    Shao, Y; Chatziioannou, A F

    2002-01-01

    We report our investigation of a positron emission tomography (PET) detector with 1 m spatial resolution. The prototype detector consists of a 9x9 array of 1x1x10 mm sup 3 lutetium oxyorthosilicate (LSO) scintillator crystals coupled to Hamamatsu R5900-M64 or R5900-C12 position sensitive PMT by either optical fibers or an optical fiber bundle. With a 511 eV gamma source, the intrinsic spatial resolution of this detector was measured to be 0.92 mm. All crystals were well resolved in the flood source histogram. The measured energy and coincidence timing resolutions were around 26% and 4 ns, respectively, demonstrating that sufficient light can be extracted from these small crystals for PET applications.

  7. 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.

  8. Topological trigger device using scintillating fibers and position-sensitive photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Kuroda, Keiichi; Dufournaud, J; Sillou, D [Laboratoire d' Annecy-le-Vieux de Physique des Particules (LAPP), 74 (France); Agoritsas, V [European Organization for Nuclear Research, Geneva (Switzerland); Bystricky, G; Lehar, F; Lesquen, A de [CEN-Saclay, 91 - Gif-sur-Yvette (France); Giacomich, R; Pauletta, G; Penzo, A; Salvato, G; Schiavon, P; Villari, A [INFN, Messina (Italy) INFN, Trieste (Italy) INFN, Udine (Italy); Gorin, A M; Meschanin, A P; Nurushev, S B; Rakhmatov, V E; Rykalin, V L; Solovyanov, V L; Vasiliev, A N; Vasil' chencko, V G [Institute for High Energy Physics, Serpukhov (USSR); Oshima, N; Yamada, R [Fermi National Accelerator Lab., Batavia, IL (USA); Takeutchi, F [Kyoto-Sanyo Univ., Kyoto (Japan); Yoshida, T [Osaka City Univ. (Japan); Akchurin, N; Onel, Y; Newsom, C

    1991-07-01

    An approach to a high quality of the Level-1 Trigger is investigated on the basis of a topological trigger device. It will be realized by using scintillating fibers and position-sensitive photomultipliers, both considered as potential candidates of new detector-components thanks to their excellent time characteristics and high radiation resistances. The device is characterized in particular by its simple concept and reliable operation supported by the mature technologies emploied. The major interests of such a scheme under LHC environments reside in its capability of selcting high pperpendicular to tracks in real time, its optional immunity against low pperpendicular to tracks and loopers, as well as its effective links to other associated devices in the complex of a vertex detector. (orig.).

  9. Depth of interaction detection with enhanced position-sensitive proportional resistor network

    International Nuclear Information System (INIS)

    Lerche, Ch.W.; Benlloch, J.M.; Sanchez, F.; Pavon, N.; Gimenez, N.; Fernandez, M.; Gimenez, M.; Sebastia, A.; Martinez, J.; Mora, F.J.

    2005-01-01

    A new method of determining the depth of interaction of γ-rays in thick inorganic scintillation crystals was tested experimentally. The method uses the strong correlation between the width of the scintillation light distribution within large continuous crystals and the γ-ray's interaction depth. This behavior was successfully reproduced by a theoretical model distribution based on the inverse square law. For the determination of the distribution's width, its standard deviation σ is computed using an enhanced position-sensitive proportional resistor network which is often used in γ-ray-imaging devices. Minor changes of this known resistor network allow the analog and real-time determination of the light distribution's 2nd moment without impairing the measurement of the energy and centroid. First experimental results are presented that confirm that the described method works correctly. Since only some cheap electronic components, but no additional detectors or crystals are required, the main advantage of this method is its low cost

  10. Position sensitive detector with semiconductor and image electron tube comprising such a detector

    International Nuclear Information System (INIS)

    Roziere, Guy.

    1977-01-01

    This invention concerns a position sensitive detector comprising a semiconducting substrate. It also concerns the electron tubes in which the detector may be incorporated in order to obtain an image formed at the tube input by an incident flux of particles or radiation. When a charged particle or group of such particles, electrons in particular, enter the space charge region of an inversely biased semiconductor diode, the energy supplied by these particles releases in the diode a certain number of electron-hole pairs which move in the field existing in the area towards the diode contacts. A corresponding current arises in the connections of this diode which constitutes the signal corresponding to the incident energy. Such a tube or chain of tubes is employed in nuclear medicine for observing parts of the human body, particularly by gamma radiation [fr

  11. A microprogrammable high-speed data collection system for position sensitive X-ray detectors

    International Nuclear Information System (INIS)

    Hashizume, H.

    1984-01-01

    A high-speed data acquisition system has been designed which collects digital data from one- and two-dimensional position sensitive X-ray detectors at a maximum average data rate of 1 MHz. The system consists of two separate fast buffer memories, a 64 K word by 20-bit main storage, two timers, a display controller, a computer interface and a keyboard, controlled by a specially designed microprogrammable microprocessor. Data collection is performed by executing a microprogram stored in the control storage; data coming from a detector are first accumulated in a small but fast buffer memory by hardware and transferred to the main storage under control of the microprogram. This design not only permits time-resolved data collections but also provides maximum speed, flexibility and cost-effectiveness simultaneously. The system also accepts data from integrated detectors such as TV cameras. The system has been designed for use in experiments at conventional and synchrotron X-ray sources. (orig.)

  12. Topological trigger device using scintillating fibres and position-sensitive photomultipliers

    CERN Document Server

    Agoritsas, V; Dufournaud, J; Giacomich, R; Gorin, A M; Kuroda, K; Meshchanin, A P; Newsom, C R; Nurushev, S B; Önel, Y M; Oshima, N; Pauletta, G; Penzo, Aldo L; Rakhmatov, V E; Rykalin, V I; Salvato, G; Schiavon, R P; Sillou, D; Solovyanov, V L; Takeutchi, F; Vasilev, V; Vasilchenko, V G; Villari, A C C; Yamada, R; Toshida, T; CERN. Geneva. Detector Research and Development Committee

    1990-01-01

    An approach to a high-quality level-1 trigger is proposed on the basis of a topological device that will be realized by using scintillating fibres and position-sensitive photomultipliers, both of which are considered as potential candidates for new detector components, thanks to their excellent time characteristics and high radiation resistance. The device is characterized, in particular, by its simple concept and reliable functioning, which are a result of the mature technologies employed. In the LHC environment, the major interests of such a scheme reside in its capability to select high ptransv. tracks in real time, in its optional immunity against low ptransv. tracks and loopers, as well as in its effective links to other associated devices within the complex of a vertex detector.

  13. Computational design and characterization of a temperature-sensitive plasmid replicon for gram positive thermophiles

    Directory of Open Access Journals (Sweden)

    Olson Daniel G

    2012-05-01

    Full Text Available Abstract Background Temperature-sensitive (Ts plasmids are useful tools for genetic engineering, but there are currently none compatible with the gram positive, thermophilic, obligate anaerobe, Clostridium thermocellum. Traditional mutagenesis techniques yield Ts mutants at a low frequency, and therefore requires the development of high-throughput screening protocols, which are also not available for this organism. Recently there has been progress in the development of computer algorithms which can predict Ts mutations. Most plasmids currently used for genetic modification of C. thermocellum are based on the replicon of plasmid pNW33N, which replicates using the RepB replication protein. To address this problem, we set out to create a Ts plasmid by mutating the gene coding for the RepB replication protein using an algorithm designed by Varadarajan et al. (1996 for predicting Ts mutants based on the amino-acid sequence of the protein. Results A library of 34 mutant plasmids was designed, synthesized and screened, resulting in 6 mutants which exhibited a Ts phenotype. Of these 6, the one with the most temperature-sensitive phenotype (M166A was compared with the original plasmid. It exhibited lower stability at 48°C and was completely unable to replicate at 55°C. Conclusions The plasmid described in this work could be useful in future efforts to genetically engineer C. thermocellum, and the method used to generate this plasmid may be useful for others trying to make Ts plasmids.

  14. Graphene oxide-Ag nanoparticles-pyramidal silicon hybrid system for homogeneous, long-term stable and sensitive SERS activity

    Science.gov (United States)

    Guo, Jia; Xu, Shicai; Liu, Xiaoyun; Li, Zhe; Hu, Litao; Li, Zhen; Chen, Peixi; Ma, Yong; Jiang, Shouzhen; Ning, Tingyin

    2017-02-01

    In our work, few layers graphene oxide (GO) were directly synthesized on Ag nanoparticles (AgNPs) by spin-coating method to fabricate a GO-AgNPs hybrid structure on a pyramidal silicon (PSi) substrate for surface-enhanced Raman scattering (SERS). The GO-AgNPs-PSi substrate showed excellent Raman enhancement effect, the minimum detected concentration for Rhodamine 6G (R6G) can reach 10-12 M, which is one order of magnitude lower than the AgNPs-PSi substrate and two order of magnitude lower than the GO-AgNPs-flat-Si substrate. The linear fit calibration curve with error bars is presented and the value of R2 of 612 and 773 cm-1 can reach 0.986 and 0.980, respectively. The excellent linear response between the Raman intensity and R6G concentrations prove that the prepared GO-AgNPs-PSi substrates can serve as good SERS substrate for molecule detection. The maximum deviations of SERS intensities from 20 positions of the GO-AgNPs-PSi substrate are less than 8%, revealing the high homogeneity of the SERS substrate. The excellent homogeneity of the enhanced Raman signals can be attributed to well-separated pyramid arrays of PSi, the uniform morphology of AgNPs and multi-functions of GO layer. Besides, the uniform GO film can effectively protect AgNPs from oxidation and endow the hybrid system a good stability and long lifetime. This GO-AgNPs-PSi substrate may provide a new way toward practical applications for the ultrasensitive and label-free SERS detection in areas of medicine, food safety and biotechnology.

  15. A two-dimensional position sensitive gas chamber with scanned charge transfer readout

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, F. E-mail: faustgr@usc.es; Iglesias, A.; Lobato, R.; Mosquera, J.; Pardo, J.; Pena, J.; Pazos, A.; Pombar, M.; Rodriguez, A

    2003-10-21

    We have constructed and tested a two-dimensional position sensitive parallel-plate gas ionization chamber with scanned charge transfer readout. The scan readout method described here is based on the development of a new position-dependent charge transfer technique. It has been implemented by using gate strips perpendicularly oriented to the collector strips. This solution reduces considerably the number of electronic readout channels needed to cover large detector areas. The use of a 25 {mu}m thick kapton etched circuit allows high charge transfer efficiency with a low gating voltage, consequently needing a very simple commutating circuit. The present prototype covers 8x8 cm{sup 2} with a pixel size of 1.27x1.27 mm{sup 2}. Depending on the intended use and beam characteristics a smaller effective pixel is feasible and larger active areas are possible. This detector can be used for X-ray or other continuous beam intensity profile monitoring.

  16. Estimation of Compton Imager Using Single 3D Position-Sensitive LYSO Scintillator: Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Taewoong; Lee, Hyounggun; Kim, Younghak; Lee, Wonho [Korea University, Seoul (Korea, Republic of)

    2017-07-15

    The performance of a Compton imager using a single three-dimensional position-sensitive LYSO scintillator detector was estimated using a Monte Carlo simulation. The Compton imager consisted of a single LYSO scintillator with a pixelized structure. The size of the scintillator and each pixel were 1.3 × 1.3 × 1.3 cm{sup 3} and 0.3 × 0.3 × 0.3 cm{sup 3}, respectively. The order of γ-ray interactions was determined based on the deposited energies in each detector. After the determination of the interaction sequence, various types of reconstruction algorithms such as simple back-projection, filtered back-projection, and list-mode maximum-likelihood expectation maximization (LM-MLEM) were applied and compared with each other in terms of their angular resolution and signal-tonoise ratio (SNR) for several γ-ray energies. The LM-MLEM reconstruction algorithm exhibited the best performance for Compton imaging in maintaining high angular resolution and SNR. The two sources of {sup 137}Cs (662 keV) could be distinguishable if they were more than 17 ◦ apart. The reconstructed Compton images showed the precise position and distribution of various radiation isotopes, which demonstrated the feasibility of the monitoring of nuclear materials in homeland security and radioactive waste management applications.

  17. The effect of mechanical stress on lateral-effect position-sensitive detector characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, H.A. [Department of Information Technology and Media, Mid-Sweden University, SE-85170 Sundsvall (Sweden)]. E-mail: Henrik.Andersson@miun.se; Mattsson, C.G. [Department of Information Technology and Media, Mid-Sweden University, SE-85170 Sundsvall (Sweden); Thungstroem, G. [Department of Information Technology and Media, Mid-Sweden University, SE-85170 Sundsvall (Sweden); Lundgren, A. [SiTek Electro Optics, Ogaerdesvaegen 13A 433 30 Partille (Sweden); Nilsson, H.-E. [Department of Information Technology and Media, Mid-Sweden University, SE-85170 Sundsvall (Sweden)

    2006-07-01

    Position-sensitive detectors (PSDs) are widely used in noncontact measurement systems. In order to minimize the size of such systems, interest has increased in mounting the PSD chip directly onto printed circuit boards (PCBs). Stress may be induced in the PSD because of the large differences in thermal expansion coefficients, as well as the long-term geometrical stability of the chip packaging. Mechanical stress has previously been shown to have an effect on the performance of semiconductors. The accuracy, or linearity, of a lateral effect PSD is largely dependent on the homogeneity of the resistive layer. Variations of the resistivity over the active area of the PSD will result in an uneven distribution of photo-generated current, and hence an error in the readout position. In this work experiments were performed to investigate the influence of anisotropic mechanical stress in terms of nonlinearity. PSD chips of 60x3 mm active area were subjected, respectively, to different amounts of compressive and tensile stress to determine the influence on the linearity.

  18. Position-sensitive proportional counter with low-resistance metal-wire anode

    International Nuclear Information System (INIS)

    Kopp, M.K.

    1980-01-01

    A position-sensitive proportional counter circuit is provided which uses a conventional (low-resistance, metal-wire anode) proportional counter for spatial resolution of an ionizing event along the anode of the counther. A pair of specially designed activecapacitance preamplifiers terminate the anode ends wherein the anode is treated as an RC line. The preamplifiers act as stabilized active capacitance loads and each is composed of a series-feedback, lownoise amplifier, a unity-gain, shunt-feedback amplifier whose output is connected through a feedback capacitor to the series-feedback amplifier input. The stabilized capacitance loading of the anode allows distributed RC-line position encoding and subsequent time difference decoding by sensing the difference in rise times of pulses at te anode ends where the difference is primarily in response to the distributed capacitance along the anode. This allows the use of lower resistance wire anodes for spatial radiation detection which simplifies the counter construction and handling of the anodes, and stabilizes the anode resistivity at high count rates

  19. Measurement of spatial dose-rate distribution using a position sensitive detector

    International Nuclear Information System (INIS)

    Emoto, T.; Torii, T.; Nozaki, T.; Ando, H.

    1994-01-01

    Recently, the radiation detectors using plastic scintillation fibers (PSF) have been developed to measure the positions exposed to radiation such as neutrons and high energy charged particles. In particular, the time of flight (TOF) method for measuring the difference of time that two directional signals of scintillation light reach both ends of a PSF is a rather simple method for the measurement of the spatial distribution of fast neutron fluence rate. It is possible to use the PSF in nuclear facility working areas because of its flexibility, small diameter and long length. In order to apply TOF method to measure spatial gamma dose rate distribution, the characteristic tests of a detector using PSFs were carried out. First, the resolution of irradiated positions and the counting efficiency were measured with collimated gamma ray. The sensitivity to unit dose rate was also obtained. The measurement of spatial dose rate distribution was also carried out. The sensor is made of ten bundled PSFs, and the experimental setup is described. The experiment and the results are reported. It was found that the PSF detector has the good performance to measure spatial gamma dose rate distribution. (K.I.)

  20. Semiautomatic imputation of activity travel diaries : use of global positioning system traces, prompted recall, and context-sensitive learning algorithms

    NARCIS (Netherlands)

    Moiseeva, A.; Jessurun, A.J.; Timmermans, H.J.P.; Stopher, P.

    2016-01-01

    Anastasia Moiseeva, Joran Jessurun and Harry Timmermans (2010), ‘Semiautomatic Imputation of Activity Travel Diaries: Use of Global Positioning System Traces, Prompted Recall, and Context-Sensitive Learning Algorithms’, Transportation Research Record: Journal of the Transportation Research Board,

  1. Position sensitive photon detectors using epitaxial InGaAs/InAlAs quantum wells

    International Nuclear Information System (INIS)

    Ganbold, T.; Antonelli, M.; Cautero, G.; Jark, H.; Eichert, D.M.; Cucini, R.; Menk, R.H.; Biasiol, G.

    2014-01-01

    This work deals with the investigation of novel position-sensitive devices based on InGaAs/InAlAs quantum wells, which could be applied to several applications of either synchrotron or conventional light sources. Such devices may be used as fast and efficient detectors due to the direct, low-energy band gap and high electron mobility at room temperature. Metamorphic In 0.75 Ga 0.25 As/In 0.75 Al 0.25 As quantum wells containing a two-dimensional electron gas were grown by molecular beam epitaxy. Two devices with size of 5 × 5 mm 2 were prepared by using optical lithography. In the first, the active layers were segmented into four electrically insulated quadrants. Indium ohmic contacts were realized on the corner of each quadrant (for readout) and on the back surface (for bias). In the second, the quantum well was left unsegmented and covered by 400 nm of Al providing a single bias electrode, while four readout electrodes were fabricated on the back side by depositing and segmenting a Ni/Ge/Au layer. Photo-generated carriers can be collected at the readout electrodes by biasing from either the QW side or the back side of the devices during beam exposure. Individual currents obtained from each electrode allow monitoring of both the position and the intensity of the impinging beam for photon energies ranging from visible to hard X-ray. Such detector prototypes were tested with synchrotron radiation. Moreover, the position of the beam can be estimated with a precision of 800 nm in the segmented QW. A lower precision of 10 μm was recorded in the unsegmented QW due to the charge diffusion through the 500-μm-thick wafer, with however a lower electronic noise due to the better uniformity of the contacts

  2. Increased sensitivity to positive social stimuli in monozygotic twins at risk of bipolar vs. unipolar disorder.

    Science.gov (United States)

    Kærsgaard, S; Meluken, I; Kessing, L V; Vinberg, M; Miskowiak, K W

    2018-05-01

    Abnormalities in affective cognition are putative endophenotypes for bipolar and unipolar disorders but it is unclear whether some abnormalities are disorder-specific. We therefore investigated affective cognition in monozygotic twins at familial risk of bipolar disorder relative to those at risk of unipolar disorder and to low-risk twins. Seventy monozygotic twins with a co-twin history of bipolar disorder (n = 11), of unipolar disorder (n = 38) or without co-twin history of affective disorder (n = 21) were included. Variables of interest were recognition of and vigilance to emotional faces, emotional reactivity and -regulation in social scenarios and non-affective cognition. Twins at familial risk of bipolar disorder showed increased recognition of low to moderate intensity of happy facial expressions relative to both unipolar disorder high-risk twins and low-risk twins. Bipolar disorder high-risk twins also displayed supraliminal attentional avoidance of happy faces compared with unipolar disorder high-risk twins and greater emotional reactivity in positive and neutral social scenarios and less reactivity in negative social scenarios than low-risk twins. In contrast with our hypothesis, there was no negative bias in unipolar disorder high-risk twins. There were no differences between the groups in demographic characteristics or non-affective cognition. The modest sample size limited the statistical power of the study. Increased sensitivity and reactivity to positive social stimuli may be a neurocognitive endophenotype that is specific for bipolar disorder. If replicated in larger samples, this 'positive endophenotype' could potentially aid future diagnostic differentiation between unipolar and bipolar disorder. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Undepleted silicon detectors

    International Nuclear Information System (INIS)

    Rancoita, P.G.; Seidman, A.

    1985-01-01

    Large-size silicon detectors employing relatively low resistivity material can be used in electromagnetic calorimetry. They can operate in strong magnetic fields, under geometric constraints and with microstrip detectors a high resolution can be achieved. Low noise large capacitance oriented electronics was developed to enable good signal-to-noise ratio for single relativistic particles traversing large area detectors. In undepleted silicon detectors, the charge migration from the field-free region has been investigated by comparing the expected peak position (from the depleted layer only) of the energy-loss of relativistic electrons with the measured one. Furthermore, the undepleted detectors have been employed in a prototype of Si/W electromagnetic colorimeter. The sensitive layer was found to be systematically larger than the depleted one

  4. Development of a high-count-rate neutron detector with position sensitivity and high efficiency

    International Nuclear Information System (INIS)

    Nelson, R.; Sandoval, J.

    1996-01-01

    While the neutron scattering community is bombarded with hints of new technologies that may deliver detectors with high-count-rate capability, high efficiency, gamma-ray insensitivity, and high resolution across large areas, only the time-tested, gas-filled 3 He and scintillation detectors are in widespread use. Future spallation sources with higher fluxes simply must exploit some of the advanced detector schemes that are as yet unproved as production systems. Technologies indicating promise as neutron detectors include pixel arrays of amorphous silicon, silicon microstrips, microstrips with gas, and new scintillation materials. This project sought to study the competing neutron detector technologies and determine which or what combination will lead to a production detector system well suited for use at a high-intensity neutron scattering source

  5. Theory and Development of Position-Sensitive Quantum Calorimeters. Degree awarded by Stanford Univ.

    Science.gov (United States)

    Figueroa-Feliciano, Enectali; White, Nicholas E. (Technical Monitor)

    2001-01-01

    Quantum calorimeters are being developed as imaging spectrometers for future X-ray astrophysics observatories. Much of the science to be done by these instruments could benefit greatly from larger focal-plane coverage of the detector (without increasing pixel size). An order of magnitude more area will greatly increase the science throughput of these future instruments. One of the main deterrents to achieving this goal is the complexity of the readout schemes involved. We have devised a way to increase the number of pixels from the current baseline designs by an order of magnitude without increasing the number of channels required for readout. The instrument is a high energy resolution, distributed-readout imaging spectrometer called a Position-Sensitive Transition-Edge Sensor (POST). A POST is a quantum calorimeter consisting of two Transition-Edge Sensors (TESS) on the ends of a long absorber capable of one-dimensional imaging spectroscopy. Comparing rise time and energy information from the two TESS, the position of the event in the POST is determined. The energy of the event is inferred from the sum of the two pulses. We have developed a generalized theoretical formalism for distributed-readout calorimeters and apply it to our devices. We derive the noise theory and calculate the theoretical energy resolution of a POST. Our calculations show that a 7-pixel POST with 6 keV saturation energy can achieve 2.3 eV resolution, making this a competitive design for future quantum calorimeter instruments. For this thesis we fabricated 7- and 15-pixel POSTS using Mo/Au TESs and gold absorbers, and moved from concept drawings on scraps of napkins to a 32 eV energy resolution at 1.5 keV, 7-pixel POST calorimeter.

  6. Cherenkov radiation-based three-dimensional position-sensitive PET detector: A Monte Carlo study.

    Science.gov (United States)

    Ota, Ryosuke; Yamada, Ryoko; Moriya, Takahiro; Hasegawa, Tomoyuki

    2018-05-01

    Cherenkov radiation has recently received attention due to its prompt emission phenomenon, which has the potential to improve the timing performance of radiation detectors dedicated to positron emission tomography (PET). In this study, a Cherenkov-based three-dimensional (3D) position-sensitive radiation detector was proposed, which is composed of a monolithic lead fluoride (PbF 2 ) crystal and a photodetector array of which the signals can be readout independently. Monte Carlo simulations were performed to estimate the performance of the proposed detector. The position- and time resolution were evaluated under various practical conditions. The radiator size and various properties of the photodetector, e.g., readout pitch and single photon timing resolution (SPTR), were parameterized. The single photon time response of the photodetector was assumed to be a single Gaussian for the simplification. The photo detection efficiency of the photodetector was ideally 100% for all wavelengths. Compton scattering was included in simulations, but partly analyzed. To estimate the position at which a γ-ray interacted in the Cherenkov radiator, the center-of-gravity (COG) method was employed. In addition, to estimate the depth-of-interaction (DOI) principal component analysis (PCA), which is a multivariate analysis method and has been used to identify the patterns in data, was employed. The time-space distribution of Cherenkov photons was quantified to perform PCA. To evaluate coincidence time resolution (CTR), the time difference of two independent γ-ray events was calculated. The detection time was defined as the first photon time after the SPTR of the photodetector was taken into account. The position resolution on the photodetector plane could be estimated with high accuracy, by using a small number of Cherenkov photons. Moreover, PCA showed an ability to estimate the DOI. The position resolution heavily depends on the pitch of the photodetector array and the radiator

  7. The Research of Screw Thread Parameter Measurement Based on Position Sensitive Detector and Laser

    International Nuclear Information System (INIS)

    Tong, Q B; Ding, Z L; Chen, J C; Ai, L L; Yuan, F

    2006-01-01

    A technique and system of measuring screw thread parameter based on the theory of laser measurement is presented in this paper, which can be carried out the automated measurement of screw thread parameter. An inspection instrument was designed and produced, which included exterior imaging system of optical path, transverse displacement measurement system, axial displacement measurement system, and a module to deal with, control and assess the data in the upper system. The inspection and estimate of the screw thread contour curve were completed by using position sensitive device (PSD) as photoelectric detector to measure the coordinate data of the screw thread contour curve in the transverse section, and using precise raster to measure the axial displacement of the precision worktable under the screw thread test criterion., computer can gives a measured result according to coordinate data of the screw thread obtained by PSD. The relation between measured spot and image is established, and optimum design of the system organization are introduced, including the image length of receiving lens focal length optical system and the choice of PSD , and some main factor affected measuring precision are analyzed. The experimental results show that the measurement uncertainty of screw thread minor diameter can reach 0. 5μm, which can meet most requests for the measurement of screw thread parameter

  8. Single-Photon Computed Tomography With Large Position-Sensitive Phototubes*

    Science.gov (United States)

    Feldmann, John; Ranck, Amoreena; Saunders, Robert S.; Welsh, Robert E.; Bradley, Eric L.; Saha, Margaret S.; Kross, Brian; Majewski, Stan; Popov, Vladimir; Weisenberger, Andrew G.; Wojcik, Randolph

    2000-10-01

    Position-sensitive photomultiplier tubes (PSPMTs) coupled to pixelated CsI(Tl) scintillators have been used with parallel-hole collimators to view the metabolism in small animals of radiopharmaceuticals tagged with ^125I. We report here our preliminary results analyzed using a tomography program^1 written in IDL programming language. The PSPMTs are mounted on a rotating gantry so as to view the subject animal from any azimuth. Preliminary results to test the tomography algorithm have been obtained by placing a variety of plastic mouse-brain phantoms (loaded with Na^125I) in front of one of the detectors and rotating the phantom in steps through 360 degrees. Results of this simulation taken with a variety of collimator hole sizes will be compared and discussed. Extentions of this technique to the use of very small PSPMTs (Hamamatsu M-64) which are capable of a very close approach to those parts of the animal of greatest interest will be described. *Supported in part by The Department of Energy, The National Science Foundation, The American Diabetes Association, The Howard Hughes Foundation and The Jeffress Trust. 1. Tomography algorithm kindly provided by Dr. S. Meikle of The Royal Prince Albert Hospital, Sydney, Australia

  9. On-line evaluation of position-sensitive detector (PSD) diffraction data

    International Nuclear Information System (INIS)

    Stansfield, R.F.D.; McIntyre, G.J.

    1985-01-01

    The amount of raw data accumulated in a single-crystal diffraction experiment using a two-dimensional Position Sensitive Detector is usually so large that it is impracticable to store it. It is therefore necessary to reduce each local three-dimensional array of counts to a Bragg intensity, in a time not longer than the average time that one reflection is active. The statistically optimum procedure comprises an estimation of the background from a large number of counts, and an integration of peak intensity within a suitable three-dimensional envelope. A typical on-line method is described, using as an example the D19 diffractometer at the Institut Max von Laue - Paul Langevin (ILL) high-flux reactor. Current methods of PSD data reduction are reviewed. These fall into three groups according to the basis of the method used to find the integration envelope: (a) statistical criteria, (b) three-dimensional sigma(I)/I analysis, and (c) pre-calculation of the resolution function. On-line data reduction imposes special requirements on diagnostics to check the precision of the reduced data, especially at the start of an experiment, when any peculiarities must be identified and allowed for in the data-reduction procedure. The diagnostic possibilities resulting from the comparison of local with global characteristics of the background and the integration envelope are discussed. (author)

  10. Peak-shape analysis for protein neutron crystallography with position-sensitive detectors

    International Nuclear Information System (INIS)

    Schoenborn, B.P.

    1983-01-01

    In neutron protein crystallography, the use of position-sensitive detectors controlled by a modern data-acquisition system permits new approaches to data-collection strategies. Instead of dealing with conventional scans, like the theta-2theta scan, that provide an integrated intensity as a function of a rotational parameter, the computer-linked counter can be used to produce a three-dimensional reflection profile. As the crystal steps (δ#betta#) through a reflection, the observed data for each step are stored in an external memory as a function of extent in 2theta and height (y) of a reflection. In this space, the reflection will be a three-dimensional distribution with dimensions determined by such basic geometrical conditions as δlambda, crystal size, mosaic spread, counter-resolution, and beam-collimation parameters. Knowledge of the interaction of these basic parameters will allow the design of optimal beam optics and will permit the delineation of the reflection from the background and permit, therefore, an accurate intensity determination. (Auth.)

  11. Optimal design of a high accuracy photoelectric auto-collimator based on position sensitive detector

    Science.gov (United States)

    Yan, Pei-pei; Yang, Yong-qing; She, Wen-ji; Liu, Kai; Jiang, Kai; Duan, Jing; Shan, Qiusha

    2018-02-01

    A kind of high accuracy Photo-electric auto-collimator based on PSD was designed. The integral structure composed of light source, optical lens group, Position Sensitive Detector (PSD) sensor, and its hardware and software processing system constituted. Telephoto objective optical type is chosen during the designing process, which effectively reduces the length, weight and volume of the optical system, as well as develops simulation-based design and analysis of the auto-collimator optical system. The technical indicators of auto-collimator presented by this paper are: measuring resolution less than 0.05″; a field of view is 2ω=0.4° × 0.4° measuring range is +/-5' error of whole range measurement is less than 0.2″. Measuring distance is 10m, which are applicable to minor-angle precise measuring environment. Aberration analysis indicates that the MTF close to the diffraction limit, the spot in the spot diagram is much smaller than the Airy disk. The total length of the telephoto lens is only 450mm by the design of the optical machine structure optimization. The autocollimator's dimension get compact obviously under the condition of the image quality is guaranteed.

  12. Imaging the electron transfer reaction of Ne2+ with Ar using position-sensitive coincidence spectroscopy

    International Nuclear Information System (INIS)

    Harper, Sarah M; Hu Wanping; Price, Stephen D

    2002-01-01

    A new experiment, employing position-sensitive detection coupled with time-of-flight mass spectrometry, has been used to investigate the single-electron transfer reaction between Ne 2+ and Ar by detecting the resulting pairs of singly charged ions in coincidence. The experimental technique allows the determination of the individual velocity vectors of the ionic products, in the centre-of-mass frame, for each reactive event detected. The experiments show that forward scattering dominates the reactivity, although a bimodal angular distribution is apparent. In addition, the spectra show that at laboratory frame collision energies from 4-14 eV the reactivity is dominated by Ne 2+ (2p 4 , 3 P) accepting an electron from an argon atom to form the ground state of Ne + together with an Ar + ion in an excited electronic level, predominantly arising from the Ar + (3s 2 3p 4 3d) configuration. The form of this reactivity, and the differences between the reactivity observed in these experiments and those performed at higher collision energies, are well reproduced by Landau-Zener theory

  13. An ancient form of position-sensitive detector - the individual counter array

    International Nuclear Information System (INIS)

    Hewat, A.W.

    1983-01-01

    Large position sensitive detectors (PSDs) have been very successful as high efficiency neutron powder diffractometers. Complete powder patterns can be obtained within minutes, making possible real-time measurements of structural changes accompanying chemical and electrochemical reactions. The angular resolution of such machines is determined by the diameter of the sample, and not simply by the resolution of the detector itself. It is argued that since sample diameters are usually 5mm to 10mm, it is possible to use an array of individual counters of similar diameter rather than a true PSD. Such a low to medium resolution individual counter array (ICA) can be made more efficient than the true PSD, produces an identical diffraction pattern, and has several practical advantages, including covering a greater solid angle. For high resolution powder diffraction, it has already been demonstrated that an ICA, in this case associated with Soller collimators, is again the most efficient solution. This is because the sample volume (and intensity) of a high resolution PSD decreases quadratically with the diameter of the sample. The only alternative to very small samples would be a large sample-detector distance, and then large vertical divergences cannot be achieved because of mechanical limitations on gas-filled PSD apertures; again intensity is lost. The resolution and efficiency of the ICA are discussed. (author)

  14. High resolution multiple sampling ionization chamber (MUSIC) sensitive to position coordinates

    International Nuclear Information System (INIS)

    Petrascu, H.; Kumagai, H.; Tanihata, I.; Petrascu, M.

    1999-01-01

    A new type of MUSIC sensitive to position coordinates is reported. The development of the first version of this type of chamber is based on the principles presented by Badhwar in 1973. The present detector will be used in experiments on fusion by using radioactive beams. This chamber due to the high resolution is suitable to identification and tracking of low Z particles. One of our goals, when we started this work, was to reduce as much as possible the Z value of particles that can be 'seen' by an ionization chamber. The resolution of the chamber was significantly improved by connecting the preamplifiers directly to the MUSIC's pads. These preamplifiers are able to work in vacuum and very low gas pressure. In this way the value of signal to noise ratio was increased by a factor of ∼10. The detector is of Frisch grid type, with the anode split into 10 active pads. It is the first model of a MUSIC with the field shared between the position grid and the anode pads. The Frisch grid was necessary because the detector is originally designed for very accurate energy measurements and particle identification. A drawing of this detector is shown. The detector itself consists of four main parts. The first one is the constant field-gradient cage, sandwiched in between the cathode and the Frisch grid. The second is the Frisch grid. The third is the position grid located under the Frisch grid. The last one is the plate with the anode pads. The cage is made of 100 μm Cu-Be wires. Every wire was tensioned with a weight representing half of its breaking limit. The Frisch grid was done on an aluminium frame, on which 20 μm W wires spaced 0.3 mm, were wound. For the position grid, 10 groups of 20 μm gold plated W wires have been used. Each group consisted of 5 wires spaced 0.9 mm and connected in parallel. The anode pads 7.8 x 60 mm 2 were perpendicular to the beam direction. Each pad and each of the position wire groups were connected to a preamplifier. The energy resolution

  15. Development of a new signal processor for tetralateral position sensitive detector based on single-chip microcomputer

    International Nuclear Information System (INIS)

    Huang Meizhen; Shi Longzhao; Wang Yuxing; Ni Yi; Li Zhenqing; Ding Haifeng

    2006-01-01

    An inherently nonlinear relation between the output current of the tetralateral position sensitive detector (PSD) and the position of the incident light spot has been found theoretically. Based on single-chip microcomputer and the theoretical relation between output current and position, a new signal processor capable of correcting nonlinearity and reducing position measurement deviation of tetralateral PSD was developed. A tetralateral PSD (S1200, 13x13 mm 2 , Hamamatsu Photonics K.K.) was measured with the new signal processor, a linear relation between the output position of the PSD, and the incident position of the light spot was obtained. In the 60% range of a 13x13 mm 2 active area, the position nonlinearity (rms) was 0.15% and the position measurement deviation (rms) was ±20 μm. Compared with traditional analog signal processor, the new signal processor is of better compatibility, lower cost, higher precision, and easier to be interfaced

  16. Depth of interaction resolution measurements for a high resolution PET detector using position sensitive avalanche photodiodes

    International Nuclear Information System (INIS)

    Yang Yongfeng; Dokhale, Purushottam A; Silverman, Robert W; Shah, Kanai S; McClish, Mickel A; Farrell, Richard; Entine, Gerald; Cherry, Simon R

    2006-01-01

    We explore dual-ended read out of LSO arrays with two position sensitive avalanche photodiodes (PSAPDs) as a high resolution, high efficiency depth-encoding detector for PET applications. Flood histograms, energy resolution and depth of interaction (DOI) resolution were measured for unpolished LSO arrays with individual crystal sizes of 1.0, 1.3 and 1.5 mm, and for a polished LSO array with 1.3 mm pixels. The thickness of the crystal arrays was 20 mm. Good flood histograms were obtained for all four arrays, and crystals in all four arrays can be clearly resolved. Although the amplitude of each PSAPD signal decreases as the interaction depth moves further from the PSAPD, the sum of the two PSAPD signals is essentially constant with irradiation depth for all four arrays. The energy resolutions were similar for all four arrays, ranging from 14.7% to 15.4%. A DOI resolution of 3-4 mm (including the width of the irradiation band which is ∼2 mm) was obtained for all the unpolished arrays. The best DOI resolution was achieved with the unpolished 1 mm array (average 3.5 mm). The DOI resolution for the 1.3 mm and 1.5 mm unpolished arrays was 3.7 and 4.0 mm respectively. For the polished array, the DOI resolution was only 16.5 mm. Summing the DOI profiles across all crystals for the 1 mm array only degraded the DOI resolution from 3.5 mm to 3.9 mm, indicating that it may not be necessary to calibrate the DOI response separately for each crystal within an array. The DOI response of individual crystals in the array confirms this finding. These results provide a detailed characterization of the DOI response of these PSAPD-based PET detectors which will be important in the design and calibration of a PET scanner making use of this detector approach

  17. Study of capillary tracking detectors with position-sensitive photomultiplier readout

    International Nuclear Information System (INIS)

    Cardini, A.; Cavasinni, V.; Di Girolamo, B.; Dolinsky, S.I.; Flaminio, V.; Golovkin, S.V.; Gorin, A.M.; Medvedkov, A.M.; Pyshev, A.I.; Tyukov, V.E.; Vasilchenko, V.G.; Zymin, K.V.

    1995-01-01

    Measurements have been carried out on light yield and attenuation length in glass capillaries filled with new liquid scintillators (LS) and compared with analogous measurements made on 0.5 mm diameter plastic fibres Kuraray SCSF-38 and 3HF. It is found that, at a distance of 1 m, the light output in the capillary filled with green LS based on 1-methylnaphthalene doped with a new dye 3M15 is greater by a factor of 2 to 3 than for plastic fibres. A tracking detector consisting of a capillary bundle read out by a 100 channel position-sensitive microchannel plate photomultiplier (2MCP-100) has been built and tested in the laboratory using a cosmic ray trigger. A comparison has been made between the performance of such a detector and that of a similar one, read out by a 96 channel Philips XP1724/A photomultiplier. It was found that a bundle made of 20μm diameter capillaries with a tapered end giving a magnification of 2.56, filled with the new IPN+3M15 liquid scintillator, read out by the 2MCP-100, provides a space resolution of σ=170μm, a two-track resolution of the same value and a hit density of n=1.9/mm for tracks crossing the detector at a distance of 20 cm from the photocathode. If the same detector is read out by the Philips XP1724/A, the space resolution becomes 200μm, the two-track resolution 600μm and the hit density n=1.7/mm. The worse performance in the latter case is caused by the larger crosstalk compared with that of the 2MCP-100 PSPM. The results indicate that a LS-filled capillary detector is a very promising device for fast fibre tracking. (orig.)

  18. A thermal-driven silicon micro xy-stage integrated with piezoresistive sensors for nano-positioning

    International Nuclear Information System (INIS)

    Choi, Young-Soo; Zhang, Yan; Lee, Dong-Weon

    2012-01-01

    This paper describes a novel micro xy-stage, driven by double-hot arm horizontal thermal micro-actuators integrated with a piezoresistive sensor (PS) for low-voltage operation and precise control. This micro xy-stage structure is linked with chevron beams and optimized to amplify the displacement generated by the micro-actuators that provide a pull force to the movable platform. The PS employed for in situ displacement detection and feedback control is fabricated at the base of a cold arm, which minimizes the influence of temperature change induced by electro-thermal heating. The micro xy-stage structure is defined through the use of a simple micromachining process, released by backside wet etching with a special tool. For an input power of approximately 44 mW, each chevron actuator provides about 16 µm and the total displacement of the platform is close to 32 µm. The sensitivity of the PS is better than 1 mV µm −1 , obtained from the amplified voltage output of the Wheatstone bridge circuit. The potential applications of the proposed micro xy-stage lie in micro- or nano-manipulation, as well as the positioning of ultra-small objects in nanotechnology. (paper)

  19. Singlet oxygen sensitizing materials based on porous silicone: photochemical characterization, effect of dye reloading and application to water disinfection with solar reactors.

    Science.gov (United States)

    Manjón, Francisco; Santana-Magaña, Montserrat; García-Fresnadillo, David; Orellana, Guillermo

    2010-06-01

    Photogeneration of singlet molecular oxygen ((1)O(2)) is applied to organic synthesis (photooxidations), atmosphere/water treatment (disinfection), antibiofouling materials and in photodynamic therapy of cancer. In this paper, (1)O(2) photosensitizing materials containing the dyes tris(4,4'-diphenyl-2,2'-bipyridine)ruthenium(II) (1, RDB(2+)) or tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (2, RDP(2+)), immobilized on porous silicone (abbreviated RDB/pSil and RDP/pSil), have been produced and tested for waterborne Enterococcus faecalis inactivation using a laboratory solar simulator and a compound parabolic collector (CPC)-based solar photoreactor. In order to investigate the feasibility of its reuse, the sunlight-exposed RDP/pSil sensitizing material (RDP/pSil-a) has been reloaded with RDP(2+) (RDP/pSil-r). Surprisingly, results for bacteria inactivation with the reloaded material have demonstrated a 4-fold higher efficiency compared to those of either RDP/pSil-a, unused RDB/pSil and the original RDP/pSil. Surface and bulk photochemical characterization of the new material (RDP/pSil-r) has shown that the bactericidal efficiency enhancement is due to aggregation of the silicone-supported photosensitizer on the surface of the polymer, as evidenced by confocal fluorescence lifetime imaging microscopy (FLIM). Photogenerated (1)O(2) lifetimes in the wet sensitizer-doped silicone have been determined to be ten times longer than in water. These facts, together with the water rheology in the solar reactor and the interfacial production of the biocidal species, account for the more effective disinfection observed with the reloaded photosensitizing material. These results extend and improve the operational lifetime of photocatalytic materials for point-of-use (1)O(2)-mediated solar water disinfection.

  20. Sensitivity Range Analysis of Infrared (IR) Transmitter and Receiver Sensor to Detect Sample Position in Automatic Sample Changer

    International Nuclear Information System (INIS)

    Syirrazie Che Soh; Nolida Yussup; Nur Aira Abdul Rahman; Maslina Ibrahim

    2016-01-01

    Sensitivity range of IR Transmitter and Receiver Sensor influences the effectiveness of the sensor to detect position of a sample. Then the purpose of this analysis is to determine the suitable design and specification the electronic driver of the sensor to gain appropriate sensitivity range for required operation. The related activities to this analysis cover electronic design concept and specification, calibration of design specification and evaluation on design specification for required application. (author)

  1. P-type silicon drift detectors

    International Nuclear Information System (INIS)

    Walton, J.T.; Krieger, B.; Krofcheck, D.; O'Donnell, R.; Odyniec, G.; Partlan, M.D.; Wang, N.W.

    1995-06-01

    Preliminary results on 16 CM 2 , position-sensitive silicon drift detectors, fabricated for the first time on p-type silicon substrates, are presented. The detectors were designed, fabricated, and tested recently at LBL and show interesting properties which make them attractive for use in future physics experiments. A pulse count rate of approximately 8 x l0 6 s -1 is demonstrated by the p-type silicon drift detectors. This count rate estimate is derived by measuring simultaneous tracks produced by a laser and photolithographic mask collimator that generates double tracks separated by 50 μm to 1200 μm. A new method of using ion-implanted polysilicon to produce precise valued bias resistors on the silicon drift detectors is also discussed

  2. Evaluation of human skin tests for potential dermal irritant and contact sensitizing products: a position paper

    NARCIS (Netherlands)

    Loveren H van; Jong WH de; Garssen J; LPI

    1998-01-01

    Prediction of human cutaneous irritation and sensitization in view of hazard identification has primarily relied on the use of laboratory animals. Such studies in laboratory animals have been very instrumental in the detection of potential contact sensitizing agents. There are however many

  3. A False Positive {sup 18}F-FDG PET/CT Scan Caused by Breast Silicone Injection

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chao Jung; Lee, Bi Fang; Yao, Wei Jen; Wu, Pei Shan; Chen, Wen Chung; Peng, Shu Lin; Chiu, Nan Tsing [Cheng Kung University Medical College and Hospital, Tainan (Turkmenistan)

    2009-04-15

    We present here the case of a 40-year-old woman with a greater than 10 year prior history of bilateral breast silicone injection and saline bag implantation. Bilateral palpable breast nodules were observed, but the ultrasound scan was suboptimal and the magnetic resonance imaging showed no gadolinium enhanced tumor. The {sup 18}F-FDG PET/CT scan showed a hypermetabolic nodule in the left breast with a 30% increase of {sup 18}F-FDG uptake on the delayed imaging, and this mimicked breast cancer. She underwent a left partial mastectomy and the pathology demonstrated a siliconoma.

  4. Position sensitive detection of nuclear radiation mediated by non equilibrium phonons at low temperatures

    Science.gov (United States)

    Pröbst, F.; Peterreins, Th.; Feilitzsch, F. v.; Kraus, H.

    1990-03-01

    Many experiments in nuclear and particle physics would benefit from the development of a device capable of detecting non-ionizing events with a low energy threshold. In this context, we report on experimental tests of a detector based on the registration of nonequilibrium phonons. The device is composed of a silicon single crystal (size: 20×10×3 mm 3) and of an array of superconducting tunnel junctions evaporated onto the surface of the crystal. The junctions serve as sensors for phonons created by absorption of nuclear radiation in the crystal. We show how pulse height analysis and the investigation of time differences between correlated pulses in different junctions can be used to obtain information about the point of absorption.

  5. Doubly versus singly positively charged oxygen ions back-scattered from a silicon surface under dynamic O2+ bombardment

    International Nuclear Information System (INIS)

    Franzreb, Klaus; Williams, Peter; Loerincik, Jan; Sroubek, Zdenek

    2003-01-01

    Mass-resolved (and emission-charge-state-resolved) low-energy ion back-scattering during dynamic O 2 + bombardment of a silicon surface was applied in a Cameca IMS-3f secondary ion mass spectrometry (SIMS) instrument to determine the bombarding energy dependence of the ratio of back-scattered O 2+ versus O + . While the ratio of O 2+ versus O + drops significantly at reduced bombarding energies, O 2+ back-scattered from silicon was still detectable at an impact energy (in the lab frame) as low as about 1.6 keV per oxygen atom. Assuming neutralization prior to impact, O 2+ ion formation in an asymmetric 16 O→ 28 Si collision is expected to take place via 'collisional double ionization' (i.e. by promotion of two outer O 2p electrons) rather than by the production of an inner-shell (O 2s or O 1s) core hole followed by Auger-type de-excitation during or after ejection. A molecular orbital (MO) correlation diagram calculated for a binary 'head-on' O-Si collision supports this interpretation

  6. Modeling of a Low-Background Spectroscopic Position-Sensitive Neutron Detector

    Energy Technology Data Exchange (ETDEWEB)

    Postovarova, Daria; Evsenin, Alexey; Gorshkov, Igor; Kuznetsov, Andrey; Osetrov, Oleg; Vakhtin, Dmitry; Yurmanov, Pavel [V.G. Khlopin Radium Institute, 194021, 28, 2nd Murinsky pr., Saint-Petersburg (Russian Federation)

    2011-12-13

    A new low-background spectroscopic direction-sensitive neutron detector that would allow one to reduce the neutron background component in passive and active neutron detection techniques is proposed. The detector is based on thermal neutron detectors surrounded by a fast neutron scintillation detector, which serves at the same time as a neutron moderator. Direction sensitivity is achieved by coincidence/anticoincidence analysis between different parts of the scintillator. Results of mathematical modeling of several detector configurations are presented.

  7. Modeling of a Low-Background Spectroscopic Position-Sensitive Neutron Detector

    International Nuclear Information System (INIS)

    Postovarova, Daria; Evsenin, Alexey; Gorshkov, Igor; Kuznetsov, Andrey; Osetrov, Oleg; Vakhtin, Dmitry; Yurmanov, Pavel

    2011-01-01

    A new low-background spectroscopic direction-sensitive neutron detector that would allow one to reduce the neutron background component in passive and active neutron detection techniques is proposed. The detector is based on thermal neutron detectors surrounded by a fast neutron scintillation detector, which serves at the same time as a neutron moderator. Direction sensitivity is achieved by coincidence/anticoincidence analysis between different parts of the scintillator. Results of mathematical modeling of several detector configurations are presented.

  8. An accelerated stress testing program for determining the reliability sensitivity of silicon solar cells to encapsulation and metallization systems

    Science.gov (United States)

    Lathrop, J. W.; Davis, C. W.; Royal, E.

    1982-01-01

    The use of accelerated testing methods in a program to determine the reliability attributes of terrestrial silicon solar cells is discussed. Different failure modes are to be expected when cells with and without encapsulation are subjected to accelerated testing and separate test schedules for each are described. Unencapsulated test cells having slight variations in metallization are used to illustrate how accelerated testing can highlight different diffusion related failure mechanisms. The usefulness of accelerated testing when applied to encapsulated cells is illustrated by results showing that moisture related degradation may be many times worse with some forms of encapsulation than with no encapsulation at all.

  9. 10 μ m-thick four-quadrant transmissive silicon photodiodes for beam position monitor application: electrical characterization and gamma irradiation effects

    Science.gov (United States)

    Rafí, J. M.; Pellegrini, G.; Quirion, D.; Hidalgo, S.; Godignon, P.; Matilla, O.; Juanhuix, J.; Fontserè, A.; Molas, B.; Pothin, D.; Fajardo, P.

    2017-01-01

    Silicon photodiodes are very useful devices as X-ray beam monitors in synchrotron radiation beamlines. Owing to Si absorption, devices thinner than 10 μ m are needed to achieve transmission over 90% for energies above 10 keV . In this work, new segmented four-quadrant diodes for beam alignment purposes are fabricated on both ultrathin (10 μ m-thick) and bulk silicon substrates. Four-quadrant diodes implementing different design parameters as well as auxiliary test structures (single diodes and MOS capacitors) are studied. An extensive electrical characterization, including current-voltage (I-V) and capacitance-voltage (C-V) techniques, is carried out on non-irradiated and gamma-irradiated devices up to 100 Mrad doses. Special attention is devoted to the study of radiation-induced charge build-up in diode interquadrant isolation dielectric, as well as its impact on device interquadrant resistance. Finally, the devices have been characterized with an 8 keV laboratory X-ray source at 108 ph/s and in BL13-XALOC ALBA Synchroton beamline with 1011 ph/s and energies from 6 to 16 keV . Sensitivity, spatial resolution and uniformity of the devices have been evaluated.

  10. Partially slotted crystals for a high-resolution γ-camera based on a position sensitive photomultiplier

    International Nuclear Information System (INIS)

    Giokaris, N.; Loudos, G.; Maintas, D.; Karabarbounis, A.; Lembesi, M.; Spanoudaki, V.; Stiliaris, E.; Boukis, S.; Gektin, A.; Pedash, V.; Gayshan, V.

    2005-01-01

    Partially slotted crystals have been designed and constructed and have been used to evaluate the performance with respect to the spatial resolution of a γ-camera based on a position-sensitive photomultiplier. It is shown that the resolution obtained with such a crystal is only slightly worse than the one obtained with a fully pixelized one whose cost, however, is much higher

  11. Application of a one-dimensional position-sensitive detector to a Kratky small-angle x-ray camera

    International Nuclear Information System (INIS)

    Russell, T.P.; Stein, R.S.; Kopp, M.K.; Zedler, R.E.; Hendricks, R.W.; Lin, J.S.

    1979-01-01

    A conventional Kratky small-angle collimation system has been modified to allow the use of a one-dimensional position-sensitive x-ray detector. The detector was designed specifically for use with a long-slit camera and has uniform sensitivity over the entire beam in the slit-length direction. Procedures for alignment of the collimation system are given, and a variety of tests of the performance of the system are presented. Among the latter are measurements of electronic noise and parasitic scattering as well as comparisons against samples which were also measured on other cameras. The good agreement of these comparisons demonstrates the success of the use of a position-sensitive detector with the Kratky collimation system

  12. Application of a one-dimensional position-sensitive detector to a Kratky small-angle x-ray camera

    Energy Technology Data Exchange (ETDEWEB)

    Russell, T.P.; Stein, R.S.; Kopp, M.K.; Zedler, R.E.; Hendricks, R.W.; Lin, J.S.

    1979-01-01

    A conventional Kratky small-angle collimation system has been modified to allow the use of a one-dimensional position-sensitive x-ray detector. The detector was designed specifically for use with a long-slit camera and has uniform sensitivity over the entire beam in the slit-length direction. Procedures for alignment of the collimation system are given, and a variety of tests of the performance of the system are presented. Among the latter are measurements of electronic noise and parasitic scattering as well as comparisons against samples which were also measured on other cameras. The good agreement of these comparisons demonstrates the success of the use of a position-sensitive detector with the Kratky collimation system.

  13. Position sensitive detection coupled to high-resolution time-of-flight mass spectrometry: Imaging for molecular beam deflection experiments

    International Nuclear Information System (INIS)

    Abd El Rahim, M.; Antoine, R.; Arnaud, L.; Barbaire, M.; Broyer, M.; Clavier, Ch.; Compagnon, I.; Dugourd, Ph.; Maurelli, J.; Rayane, D.

    2004-01-01

    We have developed and tested a high-resolution time-of-flight mass spectrometer coupled to a position sensitive detector for molecular beam deflection experiments. The major achievement of this new spectrometer is to provide a three-dimensional imaging (X and Y positions and time-of-flight) of the ion packet on the detector, with a high acquisition rate and a high resolution on both the mass and the position. The calibration of the experimental setup and its application to molecular beam deflection experiments are discussed

  14. Musical training and empathy positively impact adults’ sensitivity to infant distress

    Directory of Open Access Journals (Sweden)

    Christine E Parsons

    2014-12-01

    Full Text Available Crying is the most powerful auditory signal of infant need. Adults’ ability to perceive and respond to crying is important for infant survival and in the provision of care. This study investigated a number of listener variables that might impact on adults’ perception of infant cry distress, namely parental status, musical training and empathy. Sensitivity to infant distress was tested using a previously validated task, which experimentally manipulated distress by varying the pitch of infant cries. Parents with musical training showed a significant advantage on this task when compared with parents without. The extent of the advantage was correlated with the amount of self-reported musical training. For non-parents, individual differences in empathy were associated with task performance, with higher empathy scores corresponding to greater sensitivity to infant distress. We suggest that sensitivity to infant distress can be impacted by a number of listener variables, and may be amenable to training.

  15. 78 FR 42982 - Submission for Review: Information Collection; Questionnaire for Non-Sensitive Positions (SF 85)

    Science.gov (United States)

    2013-07-18

    ... Government civilian or military positions, or positions in private entities performing work for the Federal... adjudication. The SF 85 is completed by civilian employees of the Federal Government, military personnel, and... Security Number and provide the results to OPM. Clarifying language was added to the Authorization for...

  16. High sensitivity boron quantification in bulk silicon using the {sup 11}B(p,{alpha}{sub 0}){sup 8}Be nuclear reaction

    Energy Technology Data Exchange (ETDEWEB)

    Moro, Marcos V.; Silva, Tiago F. da; Added, Nemitala; Rizutto, Marcia A.; Tabacniks, Manfredo H. [Instituto de Fisica da Universidade de Sao Paulo, C.P. 66318, 05315-970 Sao Paulo, SP (Brazil); Neira, John B.; Neto, Joao B. F. [Institute of Research Tecnology, Cidade Universitaria, SP, 05508-091 (Brazil)

    2013-05-06

    There is a great need to quantify sub-ppm levels of boron in bulk silicon. There are several methods to analyze B in Si: Nuclear Reaction Analysis using the {sup 11}B(p,{alpha}{sub 0}){sup 8}Be reaction exhibits a quantification limit of some hundreds ppm of B in Si. Heavy Ion Elastic Recoil Detection Analysis offers a detection limit of 5 to 10 at. ppm. Secondary Ion Mass Spectrometry is the method of choice of the semiconductor industry for the analysis of B in Si. This work verifies the use of NRA to quantify B in Si, and the corresponding detection limits. Proton beam with 1.6 up to 2.6 MeV was used to obtain the cross-section of the {sup 11}B(p,{alpha}{sub 0}){sup 8}Be nuclear reaction at 170 Degree-Sign scattering angle. The results show good agreementwith literature indicating that the quantification of boron in silicon can be achieved at 100 ppm level (high sensitivity) at LAMFI-IFUSP with about 16% uncertainty. Increasing the detection solid angle and the collected beam charge, can reduce the detection limit to less than 100 ppm meeting present technological needs.

  17. Imaging monolithic silicon detector telescopes

    International Nuclear Information System (INIS)

    Amorini, F.; Sipala, V.; Cardella, G.; Boiano, C.; Carbone, B.; Cosentino, L.; Costa, E.; Di Pietro, A.; Emanuele, U.; Fallica, G.; Figuera, P.; Finocchiaro, P.; La Guidara, E.; Marchetta, C.; Pappalardo, A.; Piazza, A.; Randazzo, N.; Rizzo, F.; Russo, G.V.; Russotto, P.

    2008-01-01

    We show the results of some test beams performed on a new monolithic strip silicon detector telescope developed in collaboration with the INFN and ST-microelectronics. Using an appropriate design, the induction on the ΔE stages, generated by the charge released in the E stage, was used to obtain the position of the detected particle. The position measurement, together with the low threshold for particle charge identification, allows the new detector to be used for a large variety of applications due to its sensitivity of only a few microns measured in both directions

  18. A high resolution position sensitive X-ray MWPC for small angle X-ray diffraction

    International Nuclear Information System (INIS)

    Bateman, J.E.; Connolly, J.F.; Stephenson, R.; Tappern, G.J.

    1981-02-01

    A small sealed-off delay line readout MWPC X-ray detector has been designed and built for small angle X-ray diffraction applications. Featuring a sensitive area of 100 mm x 25 mm it yields a spatial resolution of 0.13 mm (standard deviation) with a high rate capability and good quantum efficiency for copper K radiation. (author)

  19. Enhanced sensitivity to the time variation of the fine-structure constant and mp/me in diatomic molecules: A closer examination of silicon monobromide

    International Nuclear Information System (INIS)

    Beloy, K.; Borschevsky, A.; Schwerdtfeger, P.; Flambaum, V. V.

    2010-01-01

    Recently it was pointed out that transition frequencies in certain diatomic molecules have an enhanced sensitivity to variations in the fine-structure constant α and the proton-to-electron mass ratio m p /m e due to a near cancellation between the fine structure and vibrational interval in a ground electronic multiplet [V. V. Flambaum and M. G. Kozlov, Phys. Rev. Lett. 99, 150801 (2007)]. One such molecule possessing this favorable quality is silicon monobromide. Here we take a closer examination of SiBr as a candidate for detecting variations in α and m p /m e . We analyze the rovibronic spectrum by employing the most accurate experimental data available in the literature and perform ab initio calculations to determine the precise dependence of the spectrum on variations in α. Furthermore, we calculate the natural linewidths of the rovibronic levels, which place a fundamental limit on the accuracy to which variations may be determined.

  20. Compton recoil electron tracking with silicon strip detectors

    International Nuclear Information System (INIS)

    O'Neill, T.J.; Ait-Ouamer, F.; Schwartz, I.; Tumer, O.T.; White, R.S.; Zych, A.D.

    1992-01-01

    The application of silicon strip detectors to Compton gamma ray astronomy telescopes is described in this paper. The Silicon Compton Recoil Telescope (SCRT) tracks Compton recoil electrons in silicon strip converters to provide a unique direction for Compton scattered gamma rays above 1 MeV. With strip detectors of modest positional and energy resolutions of 1 mm FWHM and 3% at 662 keV, respectively, 'true imaging' can be achieved to provide an order of magnitude improvement in sensitivity to 1.6 x 10 - 6 γ/cm 2 -s at 2 MeV. The results of extensive Monte Carlo calculations of recoil electrons traversing multiple layers of 200 micron silicon wafers are presented. Multiple Coulomb scattering of the recoil electron in the silicon wafer of the Compton interaction and the next adjacent wafer is the basic limitation to determining the electron's initial direction

  1. An overview of current developments in position-sensitive hybrid photon detectors and photo-multiplier tubes

    CERN Document Server

    Gys, Thierry

    1999-01-01

    Current developments in position-sensitive hybrid photon detectors and photo-multiplier tubes have stimulated increased interest from a variety of fields such as astronomy, biomedical imaging and high- energy physics. These devices are sensitive to single photons over a photon energy spectrum defined by the transmission of the optical entrance window and the photo-cathode type. Their spatial resolution ranges from a few millimeters for pad hybrid photon detectors and multi-anode photo-multiplier tubes down to a few tens of microns for pixel hybrid photon detectors and electron-bombarded charge-coupled devices. Basic technological and design aspects are assessed in this paper. (21 refs).

  2. Sensitivity of equatorial Pacific and Indian Ocean watermasses to the position of the Indonesian Throughflow

    Science.gov (United States)

    Rodgers, Keith B.; Latif, Mojib; Legutke, Stephanie

    2000-09-01

    The sensitivity of the thermal structure of the equatorial Pacific and Indian Ocean pycnoclines to a model's representation of the Indonesian Straits connecting the two basins is investigated. Two integrations are performed using the global HOPE ocean model. The initial conditions and surface forcing for both cases are identical; the only difference between the runs is that one has an opening for the Indonesian Straits which spans the equator on the Pacific side, and the other has an opening which lies fully north of the equator. The resulting sensitivity throughout much of the upper ocean is greater than 0.5°C for both the equatorial Indian and Pacific. A realistic simulation of net Indonesian Throughflow (ITF) transport (measured in Sverdrups) is not sufficient for an adequate simulation of equatorial watermasses. The ITF must also contain a realistic admixture of northern and southern Pacific source water.

  3. A fast position sensitive photodetector based on a CsI reflective photocathode

    International Nuclear Information System (INIS)

    Arnold, R.; Christophel, E.; Guyonnet, J.L.

    1991-01-01

    A fast detector was built for UV photon detection that depends on a CsI sensitized pad cathode. The rapidity of the detector is compared with that of a more classical chamber filled with photosensitive gases such as TEA or TMAE. Estimates of the quantum yield of the photocathode at 160 and 200 nm are given. The performances obtained make it a good photodetector candidate to be operated at high luminosity accelerators. (author) 7 refs., 19 figs

  4. ISPA (imaging silicon pixel array) experiment

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    The ISPA tube is a position-sensitive photon detector. It belongs to the family of hybrid photon detectors (HPD), recently developed by CERN and INFN with leading photodetector firms. HPDs confront in a vacuum envelope a photocathode and a silicon detector. This can be a single diode or a pixelized detector. The electrons generated by the photocathode are efficiently detected by the silicon anode by applying a high-voltage difference between them. ISPA tube can be used in high-energy applications as well as bio-medical and imaging applications.

  5. A sulfur–microporous carbon composite positive electrode for lithium/sulfur and silicon/sulfur rechargeble batteries

    Directory of Open Access Journals (Sweden)

    Takuya Takahashi

    2015-12-01

    Full Text Available Sulfur is an advantageous material as a promising next-generation positive electrode material for high-energy lithium batteries due to a high theoretical capacity of 1672 mA h g−1 although its discharge potential is somewhat modest: ca. 2 V vs Li/Li+. However, a sulfur positive electrode has some crucial problems for practical use, which are mainly attributed to the dissolution of its intermediate products in charge–discharge processes. In order to resolve the dissolution problem of lithium polysulfide, we attempted to synthesize a sulfur–microporous activated carbon (AC composite positive electrode. Moreover, we have systematically researched the battery performance of sulfur–microporous AC positive electrode with variations of electrolytes as well as negative electrodes, and found its promising positive electrode performance for a next-generation rechargeable battery.

  6. Sensitivity of peak positions to flight-path parameters in a deep-inelastic scattering neutron TOF spectrometer

    International Nuclear Information System (INIS)

    Gray, E.MacA.; Chatzidimitriou-Dreismann, C.A.; Blach, T.P.

    2012-01-01

    The effects of small changes in flight-path parameters (primary and secondary flight paths, detector angles), and of displacement of the sample along the beam axis away from its ideal position, are examined for an inelastic time-of-flight (TOF) neutron spectrometer, emphasising the deep-inelastic regime. The aim was to develop a rational basis for deciding what measured shifts in the positions of spectral peaks could be regarded as reliable in the light of the uncertainties in the calibrated flight-path parameters. Uncertainty in the length of the primary or secondary flight path has the least effect on the positions of the peaks of H, D and He, which are dominated by the accuracy of the calibration of the detector angles. This aspect of the calibration of a TOF spectrometer therefore demands close attention to achieve reliable outcomes where the position of the peaks is of significant scientific interest and is discussed in detail. The corresponding sensitivities of the position of peak of the Compton profile, J(y), to flight-path parameters and sample position are also examined, focusing on the comparability across experiments of results for H, D and He. We show that positioning the sample to within a few mm of the ideal position is required to ensure good comparability between experiments if data from detectors at high forward angles are to be reliably interpreted.

  7. Successful use of a linear position-sensitive neutron detector in solid state physics and materials science

    International Nuclear Information System (INIS)

    Schefer, J.; Fischer, P.; Heer, H.; Isacson, A.; Koch, M.; Thut, R.

    1991-01-01

    The double axis multicounter diffractometer (DMC) installed at the 10 MW reactor SAPHIR (PSI) has been designed as a good flux-good resolution (presently Δd/d≥4x10 -3 ) neutron poder diffractometer. The detector bank is based on a commercial position-sensitive linear BF 3 detector which may be automatically and precisely positioned on air cushions on inexpensive floors. This detector type has an 80deg angular opening, not allowing any standard collimation in front of the detector. We therefore developed an oscillating collimator system allowing easy use of the instrument even with sample environments such as a dilution cryostat. (orig.)

  8. Istaroxime, a positive inotropic agent devoid of proarrhythmic properties in sensitive chronic atrioventricular block dogs.

    Science.gov (United States)

    Bossu, Alexandre; Kostense, Amée; Beekman, Henriette D M; Houtman, Marien J C; van der Heyden, Marcel A G; Vos, Marc A

    2018-05-10

    Current inotropic agents in heart failure therapy associate with low benefit and significant adverse effects, including ventricular arrhythmias. Istaroxime, a novel Na + /K + -transporting ATPase inhibitor, also stimulates SERCA2a activity, which would confer improved inotropic and lusitropic properties with less proarrhythmic effects. We investigated hemodynamic, electrophysiological and potential proarrhythmic and antiarrhythmic effects of istaroxime in control and chronic atrioventricular block (CAVB) dogs sensitive to drug-induced Torsades de Pointes arrhythmias (TdP). In isolated normal canine ventricular cardiomyocytes, istaroxime (0.3-10 μM) evoked no afterdepolarizations and significantly shortened action potential duration (APD) at 3 and 10 μM. Istaroxime at 3 μg/kg/min significantly increased left ventricular (LV) contractility (dP/dt + ) and relaxation (dP/dt-) respectively by 81 and 94% in anesthetized control dogs (n = 6) and by 61 and 49% in anesthetized CAVB dogs (n = 7) sensitive to dofetilide-induced TdP. While istaroxime induced no ventricular arrhythmias in control conditions, only single ectopic beats occurred in 2/7 CAVB dogs, which were preceded by increase of short-term variability of repolarization (STV) and T wave alternans in LV unipolar electrograms. Istaroxime pre-treatment (3 μg/kg/min for 60 min) did not alleviate dofetilide-induced increase in repolarization and STV, and mildly reduced incidence of TdP from 6/6 to 4/6 CAVB dogs. In six CAVB dogs with dofetilide-induced TdP, administration of istaroxime (90 μg/kg/5 min) suppressed arrhythmic episodes in two animals. Taken together, inotropic and lusitropic properties of istaroxime in CAVB dogs were devoid of significant proarrhythmic effects in sensitive CAVB dogs, and istaroxime provides a moderate antiarrhythmic efficacy in prevention and suppression of dofetilide-induced TdP. Copyright © 2018. Published by Elsevier Ltd.

  9. Design and Performance Analysis of Laser Displacement Sensor Based on Position Sensitive Detector (PSD)

    International Nuclear Information System (INIS)

    Song, H X; Wang, X D; Ma, L Q; Cai, M Z; Cao, T Z

    2006-01-01

    By using PSD as sensitive element, and laser diode as emitting element, laser displacement sensor based on triangulation method has been widely used. From the point of view of design, sensor and its performance were studied. Two different sensor configurations were described. Determination of the dimension, sensing resolution and comparison of the two different configurations were presented. The factors affecting the performance of the laser displacement sensor were discussed and two methods, which can eliminate the affection of dark current and environment light, are proposed

  10. A detector system for two-dimensional, position-sensitive detection of neutrons and gamma quanta

    International Nuclear Information System (INIS)

    Scholz, A.

    1988-08-01

    While the well-known Anger Camera utilizes a large number of photomultiplier tubes, which are arranged in a regular array behind a scintillation crystal, the new detector system makes use of electron optics to transfer the scintillation image of a large scintillation crystal (Li-6-glass) onto a small position detector. Because of this, only few photodetectors are required for position readout, associated with only a small number of amplifier chains and a very simple position reconstruction algorithm. The reduced complexity of the readout electronics ultimately leads to an improved maintainability and reliability of the detector system. A prototype of the new detector system was built and tested. After giving an overview on already known and realized detector configurations, the basic considerations, which led to the final detector design, will be explained. Different methods of detector readout and position determination are discussed. Measurement results which were obtained with the prototype detector system are presented and explained by means of simulation calculations. (orig./HP) [de

  11. Endocrine sensitivity of the receptor-positive T61 human breast carcinoma serially grown in nude mice

    DEFF Research Database (Denmark)

    Brünner, N; Spang-Thomsen, M; Skovgaard Poulsen, H

    1985-01-01

    A study was made on the effect of ovariectomy, 17 beta-oestradiol, and tamoxifen on the oestrogen and progesterone receptor-positive T61 human breast carcinoma grown in nude mice. The effect of the treatment was evaluated by the specific growth delay calculated on the basis of Gompertz growth cur...... but is not a sufficiently clear marker to allow prediction of the endocrine sensitivity of individual breast tumours....

  12. Silicone metalization

    Energy Technology Data Exchange (ETDEWEB)

    Maghribi, Mariam N. (Livermore, CA); Krulevitch, Peter (Pleasanton, CA); Hamilton, Julie (Tracy, CA)

    2008-12-09

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  13. Position sensitive X-ray or X-ray detector and 3-D-tomography using same

    International Nuclear Information System (INIS)

    1975-01-01

    A fan-shaped beam of penetrating radiation, such as X-ray or γ-ray radiation, is directed through a slice of the body to be analyzed into a position sensitive detector for deriving a shadowgraph of transmission or absorption of the penetrating radiation by the body. A number of such shadowgraphs are obtained for different angles of rotation of the fan-shaped beam relative to the center of the slice being analyzed. The detected fan beam shadowgraph data is reordered into shadowgraph data corresponding to sets of parallel paths of radiation through the body. The reordered parallel path shadowgraph data is then convoluted in accordance with a 3-D reconstruction method by convolution in a computer to derive a 3-D reconstructed tomograph of the body under analysis. In a preferred embodiment, the position sensitive detector comprises a multiwire detector wherein the wires are arrayed parallel to the direction of the divergent penetrating rays to be detected. A focussed grid collimator is interposed between the body and the position sensitive detector for collimating the penetrating rays to be detected. The source of penetrating radiation is preferably a monochromatic source

  14. Position sensitivity of the proposed segmented germanium detectors for the DESPEC project

    International Nuclear Information System (INIS)

    Khaplanov, A.; Tashenov, S.; Cederwall, B.

    2009-01-01

    The DESPEC HPGe array is a part of the NuSTAR project at FAIR, Germany. It is aimed at the spectroscopy of the stopped decaying exotic nuclei. Segmented γ-ray tracking detectors are proposed for this array in order to maximize detection efficiency and background suppression when searching for very rare events. Two types of detector modules-stacks of three 16-fold segmented planar crystals and 12- and 16-fold segmented clover detectors-have been investigated and compared from the point of view of the achievable position resolution using pulse shape analysis (PSA). To this end, detector signals from realistic γ-ray interactions have been calculated. These signals were treated by PSA in order to reconstruct the photon interaction locations. Comparing the initial interaction locations to the reconstructed ones, it was found that the double-sided strip planar detector yielded position reconstruction errors at least a factor 2 lower than the other detectors considered.

  15. Two-dimensional position-sensitive detectors for small-angle neutron scattering

    International Nuclear Information System (INIS)

    McElhaney, S.A.; Vandermolen, R.I.

    1990-05-01

    In this paper, various detectors available for small angle neutron scattering (SANS) are discussed, along with some current developments being actively pursued. A section has been included to outline the various methodologies of position encoding/decoding with discussions on trends and limitations. Computer software/hardware vary greatly from institute and experiment and only a general discussion is given to this area. 85 refs., 33 figs

  16. Output pulse-shapes of position-sensitive proportional counters using high resistance single wire

    International Nuclear Information System (INIS)

    Iwatani, Kazuo; Nishiyama, Fumitaka; Hasai, Hiromi

    1980-01-01

    The measurements and model analysis of the output pulse-shapes from a single wire proportional counter (SWPC) which has a high resistance anode are described. The characteristics of the observed pulse-shapes are determined by only one parameter which is a function of anode resistance and load resistance and they are reproduced by a simple model. Using this model, the methods for position read-out are discussed in a systematical way. (author)

  17. Time-of-flight position-sensitive x-ray detection

    International Nuclear Information System (INIS)

    Mowat, J.W.

    1981-01-01

    A new method for recording beam-foil time-of-flight data is described. A stationary, side-window, position-senstive proportional counter, oriented with anode wire parallel to the ion beam, views the decay in flight of excited ions through a Soller slit x-ray collimator. In contrast to the standard method, the exciter foil, placed within or upstream from the field of view, is not moved during the acquisition of a decay curve. Each point on the anode acts like an independent detector seeing a unique segment of the ion beam. The correspondence between the downstream distance at which an ion decays and the position along the anode at which the x-ray is detected makes a pulse-height spectrum of position pulses equivalent to a time-of-flight decay curve. Thus an entire decay curve can now be acquired without moving the foil. Increased efficiency is the most significant improvement over the standard method in which the radiation detector views only a small segment of the flight path at any one time. Experiments using translating foils are subject to a spurious dependence of x-ray intensity on foil position if the foil is non-uniform (or non-uniformly aged) and wobbles as it moves. This effect is eliminated here. Foil aging effects which influence excitation rates and introduce a slowly varying time dependence of the x-ray intensity are automatically normalized by this multichannel technique. The application of this method to metastable x-ray emitting states of low-Z ions are discussed

  18. Gram positive and Gram negative bacteria differ in their sensitivity to cold plasma

    Science.gov (United States)

    Mai-Prochnow, Anne; Clauson, Maryse; Hong, Jungmi; Murphy, Anthony B.

    2016-12-01

    Cold atmospheric-pressure plasma (CAP) is a relatively new method being investigated for antimicrobial activity. However, the exact mode of action is still being explored. Here we report that CAP efficacy is directly correlated to bacterial cell wall thickness in several species. Biofilms of Gram positive Bacillus subtilis, possessing a 55.4 nm cell wall, showed the highest resistance to CAP, with less than one log10 reduction after 10 min treatment. In contrast, biofilms of Gram negative Pseudomonas aeruginosa, possessing only a 2.4 nm cell wall, were almost completely eradicated using the same treatment conditions. Planktonic cultures of Gram negative Pseudomonas libanensis also had a higher log10 reduction than Gram positive Staphylococcus epidermidis. Mixed species biofilms of P. aeruginosa and S. epidermidis showed a similar trend of Gram positive bacteria being more resistant to CAP treatment. However, when grown in co-culture, Gram negative P. aeruginosa was more resistant to CAP overall than as a mono-species biofilm. Emission spectra indicated OH and O, capable of structural cell wall bond breakage, were present in the plasma. This study indicates that cell wall thickness correlates with CAP inactivation times of bacteria, but cell membranes and biofilm matrix are also likely to play a role.

  19. Development of a silicon microstrip detector with single photon sensitivity for fast dynamic diffraction experiments at a synchrotron radiation beam

    Science.gov (United States)

    Arakcheev, A.; Aulchenko, V.; Kudashkin, D.; Shekhtman, L.; Tolochko, B.; Zhulanov, V.

    2017-06-01

    Time-resolved experiments on the diffraction of synchrotron radiation (SR) from crystalline materials provide information on the evolution of a material structure after a heat, electron beam or plasma interaction with a sample under study. Changes in the material structure happen within a microsecond scale and a detector with corresponding parameters is needed. The SR channel 8 of the VEPP-4M storage ring provides radiation from the 7-pole wiggler that allows to reach several tens photons within one μs from a tungsten crystal for the most intensive diffraction peak. In order to perform experiments that allow to measure the evolution of tungsten crystalline structure under the impact of powerful laser beam, a new detector is developed, that can provide information about the distribution of a scattered SR flux in space and its evolution in time at a microsecond scale. The detector is based on the silicon p-in-n microstrip sensor with DC-coupled metal strips. The sensor contains 1024 30 mm long strips with a 50 μm pitch. 64 strips are bonded to the front-end electronics based on APC128 ASICs. The APC128 ASIC contains 128 channels that consist of a low noise integrator with 32 analogue memory cells each. The integrator equivalent noise charge is about 2000 electrons and thus the signal from individual photons with energy above 40 keV can be observed. The signal can be stored at the analogue memory with 10 MHz rate. The first measurements with the beam scattered from a tungsten crystal with energy near 60 keV demonstrated the capability of this prototype to observe the spatial distribution of the photon flux with the intensity from below one photon per channel up to 0~10 photons per channel with a frame rate from 10 kHz up to 1 MHz.

  20. A general technique for characterizing x-ray position sensitive arrays

    International Nuclear Information System (INIS)

    Dufresne, E.; Bruning, R.; Sutton, M.; Stephenson, G.B.

    1994-03-01

    We present a general statistical technique for characterizing x-ray sensitive linear diode arrays and CCD arrays. We apply this technique to characterize the response of a linear diode array, Princeton Instrument model X-PDA, and a virtual phase CCD array, TI 4849, to direct illumination by x-rays. We find that the response of the linear array is linearly proportional to the incident intensity and uniform over its length to within 2 %. Its quantum efficiency is 38 % for Cu K α x-rays. The resolution function is evaluated from the spatial autocorrelation function and falls to 10 % of its peak value after one pixel. On the other hand, the response of the CCD detecting system to direct x-ray exposure is non-linear. To properly quantify the scattered x-rays, one must correct for the non- linearity. The resolution is two pixels along the serial transfer direction. We characterize the noise of the CCD and propose a model that takes into account the non-linearity and the resolution function to estimate the quantum efficiency of the detector. The quantum efficiency is 20 %

  1. Temporomandibular joint arthroplasty for osteoarthrosis: A series of 24 patients that received a uni- or bilateral inter-positional silicone sheet.

    Science.gov (United States)

    Boutault, F; Cavallier, Z; Lauwers, F; Prevost, A

    2018-06-01

    To evaluate mid-term results from using a silicone sheet for inter-positional arthroplasty in moderate or severe cases of osteoarthrosis of the temporo-mandibular joint (TMJ). To also determine any remaining indications from this method. This retrospective study included patients that underwent surgery between 2008 and 2016. Pre- and post-operative mouth opening (MO), according to inter-incisal distance (mm) and pain score (PS: 0=no pain to 4=very severe pain) were recorded for 24 patients. Patients were divided according to thickness of the silicone sheet (group A: 1.0 mm, group B: 1.5 mm). The cohort included 22 females (92%). Mean age at surgery was 55 years±13 (26-80). Mean length of follow-up was 26 months±24 (6-80). Mean improvement in MO was 8.2 mm (+33%) and of PS was 1.7 (-68%). MO was not improved for two patients and worsened for one. PS score improved for all patients. No statistical difference was found between groups A and B. There was also a tendency for degradation of outcomes over time. The poor reputation of prosthetic discoplasty was not as evident in our series, even though anatomical and functional status seemed to deteriorate over time. This is because total-joint prosthetic replacement is often proposed instead. However, for elderly or fragile patients that have severe pain, and regarding cost-benefit aspects, conventional arthroplasty can still be discussed, especially since French national health-care insurance does not yet support TMJ prosthetic replacement for osteoarthrosis. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  2. Amazingly resilient Indigenous people! Using transformative learning to facilitate positive student engagement with sensitive material.

    Science.gov (United States)

    Jackson, Debra; Power, Tamara; Sherwood, Juanita; Geia, Lynore

    2013-12-01

    If health professionals are to effectively contribute to improving the health of Indigenous people, understanding of the historical, political, and social disadvantage that has lead to health disparity is essential. This paper describes a teaching and learning experience in which four Australian Indigenous academics in collaboration with a non-Indigenous colleague delivered an intensive workshop for masters level post-graduate students. Drawing upon the paedagogy of Transformative Learning, the objectives of the day included facilitating students to explore their existing understandings of Indigenous people, the impact of ongoing colonisation, the diversity of Australia's Indigenous people, and developing respect for alternative worldviews. Drawing on a range of resources including personal stories, autobiography, film and interactive sessions, students were challenged intellectually and emotionally by the content. Students experienced the workshop as a significant educational event, and described feeling transformed by the content, better informed, more appreciative of other worldviews and Indigenous resilience and better equipped to contribute in a more meaningful way to improving the quality of health care for Indigenous people. Where this workshop differs from other Indigenous classes was in the involvement of an Indigenous teaching team. Rather than a lone academic who can often feel vulnerable teaching a large cohort of non-Indigenous students, an Indigenous teaching team reinforced Indigenous authority and created an emotionally and culturally safe space within which students were allowed to confront and explore difficult truths. Findings support the value of multiple teaching strategies underpinned by the theory of transformational learning, and the potential benefits of facilitating emotional as well as intellectual student engagement when presenting sensitive material.

  3. Modern trends in position-sensitive neutron detectors development for condensed matter research

    International Nuclear Information System (INIS)

    Belushkin, A.V.

    2007-01-01

    Detecting neutrons is a more complicated task compared to the detection of ionizing particles or ionizing radiation. This is why the variety of neutron detectors is much more limited. Meanwhile, different types of neutron experiments pose specific and often contradictory requirements for detector characteristics. For experiments on the high-intensity neutron sources, the high counting rate is one of the key issues. This is very important, for example, for small-angle neutron scattering and neutron reflectometry. For other experiments, characteristics like detection efficiency, high position resolution, high time resolution, neutron/gamma discrimination, large-area imaging, or compactness, are very important. Today, the cost of the detector also became one of the most important factors. There is no single type of detector which satisfies all the above criteria. Therefore, compromise is inevitable and some of the characteristics are trade off in favor of others. The present report gives an overview of detector systems presently operating at the leading neutron scattering facilities as well as some development work around the globe

  4. Position sensitive plastic scintillating fibre-detectors for heavy ion detection

    Energy Technology Data Exchange (ETDEWEB)

    Scholl, Sebastian; Tscheuschner, Joachim; Paschalis, Stefanos; Aumann, Thomas; Scheit, Heiko [Institut fuer Kernphysik, Technische Universitaet Darmstadt (Germany)

    2016-07-01

    The R{sup 3}B (Reactions with Relativistic Radioactive Beams) experiment at FAIR will be able to perform kinematically complete measurements of reactions with relativistic heavy-ion beams up to 1 AGeV. In order to track the beam before the target and to determine the mass number of the scattered nucleus after the reaction, five fibre detectors with sizes between 10.24 x 10.24 cm{sup 2} and 120 x 80 cm{sup 2} are going to be built for the R{sup 3}B setup. These fibre detectors will provide x-y-position of the trajectory of charged particles after the reaction target. The light from the fibre detector is sensed using MPPCs (Multi Pixel Photon Counter). For the readout of the MPPCs we test different electronics. In this contribution we present results obtained using an α-source and a LED light source to generate light in the fibre and use the PADI-VFTX for readout.

  5. Silicon radiation detectors: materials and applications

    International Nuclear Information System (INIS)

    Walton, J.T.; Haller, E.E.

    1982-10-01

    Silicon nuclear radiation detectors are available today in a large variety of sizes and types. This profusion has been made possible by the ever increasing quality and diameter silicon single crystals, new processing technologies and techniques, and innovative detector design. The salient characteristics of the four basic detector groups, diffused junction, ion implanted, surface barrier, and lithium drift are reviewed along with the silicon crystal requirements. Results of crystal imperfections detected by lithium ion compensation are presented. Processing technologies and techniques are described. Two recent novel position-sensitive detector designs are discussed - one in high-energy particle track reconstruction and the other in x-ray angiography. The unique experimental results obtained with these devices are presented

  6. A novel resveratrol-salinomycin combination sensitizes ER-positive breast cancer cells to apoptosis.

    Science.gov (United States)

    Venkatadri, Rajkumar; Iyer, Anand Krishnan V; Kaushik, Vivek; Azad, Neelam

    2017-08-01

    Resveratrol is a dietary compound that has been widely reported for its anticancer activities. However, successful extrapolation of its effects to pre-clinical studies is met with limited success due to inadequate bioavailability. We investigated the potential of combination therapy to improve the efficacy of resveratrol in a more physiologically relevant dose range. The effect of resveratrol on canonical Wnt signaling was evaluated by Western blotting. Wnt modulators HLY78 (activator) and salinomycin (inhibitor) were evaluated in combination with resveratrol for their effect on breast cancer cell viability (MTT assay), cell cycle progression and apoptosis (Western blotting). Bliss independency model was used to evaluate combinatorial effects of resveratrol-salinomycin combination. Resveratrol downregulated canonical Wnt signaling proteins in treated breast cancer cells (MCF-7, MDA-MB-231 and MDA-MB-468) in the dose range of 50-200μM, which also affected cellular viability. However, at very low doses (0-50μM), resveratrol exhibited no cellular toxicity. Co-treatment with salinomycin significantly potentiated the anti-cancer effects of resveratrol, whereas HLY78 co-treatment had minimal effect. Bliss independency model revealed that Wnt inhibition synergistically potentiates the effects of resveratrol in MCF-7 and BT474 cells. Significantly downregulated canonical Wnt signaling proteins and marker of epithelial-mesenchymal transition (EMT), vimentin were observed in cells treated with resveratrol-salinomycin combination. Cell cycle arrest, caspase activation and apoptosis induction in cells treated with resveratrol-salinomycin combination further confirmed the efficacy of the combination. We report a novel resveratrol-salinomycin combination for targeting ER-positive breast cancer cells and present evidence for successful pre-clinical implementation of resveratrol. Copyright © 2017 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban

  7. Data acquisition system for linear position sensitive detector based neutron diffractometer

    International Nuclear Information System (INIS)

    Pande, S.S.; Borkar, S.P.; Behere, A.; Prafulla, S.; Srivastava, V.D.; Mukhopadhyaya, P.K.; Ghodgaonkar, M.D.; Kataria, S.K.

    2003-03-01

    This data acquisition system is developed to serve the requirements of various linear 1PSD based neutron diffractometers. A neutron diffractometer uses a neutron beam as a probe to study the crystallographic properties of materials. Presently two multi-PSD and two single-PSD diffractometers are commissioned and a few more are being installed in Dhruva. This data acquisition system is installed at each of these - diffractometers. Different requirements of individual diffractometers were studied and reconciled to design a single data acquisition system, which can be easily configured or customized for individual setups. The charge division in a linear PSD is converted to a position output with the help of an RDC (Ratio ADC). The ftont-end electronics, which consist of preamplifiers and shaping amplifiers, provide an interface between a PSD and an RDC. A PC add-on card is designed around a Transputer. It can interface 16 RDCs, a few motor controls and on/off controls. Data acquisition and other controls are implemented in the Transputer program. A front-end Windows98 application merges the raw data of different RDCs to obtain the equiangular data. Through software the data acquisition system can be configured for diffetent diffractometers. Commercially available hardware is also integrated as,a part of the data acquisition system in some of the setups. The data acquisition system is working reliably as a part of two single PSD and two multi-PSD diffractometers. It can handle data rates upto 15 K/Sec without any loss of counts. It has played a significant role in providing improved throughput and utilization ofvarious diffractometers. The'data acquisition system and its different applications are presented in this report. (author)

  8. Detection of charged particles in amorphous silicon layers

    International Nuclear Information System (INIS)

    Perez-Mendez, V.; Morel, J.; Kaplan, S.N.; Street, R.A.

    1986-02-01

    The successful development of radiation detectors made from amorphous silicon could offer the possibility for relatively easy construction of large area position-sensitive detectors. We have conducted a series of measurements with prototype detectors, on signals derived from alpha particles. The measurement results are compared with simple model calculations, and projections are made of potential applications in high-energy and nuclear physics

  9. A primary scintillation gated high pressure position sensitive gas scintillation proportional counter (HPGSPC) for applications to x-ray astronomy

    International Nuclear Information System (INIS)

    Giarrusso, S.; Manzo, G.; Re, S.

    1985-01-01

    The authors describe a new instrument for x-ray astronomy. The instrument, based on a high pressure (5 atm.), xenon filled, position sensitive Gas Scintillation Proportional counter (HPGSPC) is expected to feature an energy resolution better than 4% at 60 keV, an angular resolution of approximately 20 arc-minutes over the full energy range (4 to 100 keV) and a field of view (FOV) of up to 30x30 degrees. A prototype flight unit of the gas cell on which the instrument is based is presently under technological development in the framework of the SAX project

  10. Electrophoresis of biomass decomposition products and position sensitive detection of the separated C-14 labelled substrates by plastic scintillator measurements

    International Nuclear Information System (INIS)

    Gruenwald, M.

    1985-12-01

    The subject of this work is separation and analysis of hydrothermally decomposed biomass solution by zone electrophoresis of charged hydrocarbon-borate complexes. The first half is dedicated to the electrophoresis. The second half describes a new evaluation method for chromatographs and electropherograms by position sensitive detection of C-14 β radiation in a 1 mm thick plastic scintillator. This method is applied to hydrothermally decomposed (U-C-14)-D glucose solutions and the results are compared to conventional chromatography. Performance numbers of the method are given. Extension to isoelectrically focused gels is also considered. (G.Q.)

  11. Design Optimization and Fabrication of High-Sensitivity SOI Pressure Sensors with High Signal-to-Noise Ratios Based on Silicon Nanowire Piezoresistors

    Directory of Open Access Journals (Sweden)

    Jiahong Zhang

    2016-10-01

    Full Text Available In order to meet the requirement of high sensitivity and signal-to-noise ratios (SNR, this study develops and optimizes a piezoresistive pressure sensor by using double silicon nanowire (SiNW as the piezoresistive sensing element. First of all, ANSYS finite element method and voltage noise models are adopted to optimize the sensor size and the sensor output (such as sensitivity, voltage noise and SNR. As a result, the sensor of the released double SiNW has 1.2 times more sensitivity than that of single SiNW sensor, which is consistent with the experimental result. Our result also displays that both the sensitivity and SNR are closely related to the geometry parameters of SiNW and its doping concentration. To achieve high performance, a p-type implantation of 5 × 1018 cm−3 and geometry of 10 µm long SiNW piezoresistor of 1400 nm × 100 nm cross area and 6 µm thick diaphragm of 200 µm × 200 µm are required. Then, the proposed SiNW pressure sensor is fabricated by using the standard complementary metal-oxide-semiconductor (CMOS lithography process as well as wet-etch release process. This SiNW pressure sensor produces a change in the voltage output when the external pressure is applied. The involved experimental results show that the pressure sensor has a high sensitivity of 495 mV/V·MPa in the range of 0–100 kPa. Nevertheless, the performance of the pressure sensor is influenced by the temperature drift. Finally, for the sake of obtaining accurate and complete information over wide temperature and pressure ranges, the data fusion technique is proposed based on the back-propagation (BP neural network, which is improved by the particle swarm optimization (PSO algorithm. The particle swarm optimization–back-propagation (PSO–BP model is implemented in hardware using a 32-bit STMicroelectronics (STM32 microcontroller. The results of calibration and test experiments clearly prove that the PSO–BP neural network can be effectively applied

  12. Characterization of an amorphous silicon flat panel for controlling the positioning accuracy of sheet; Caracterizacion de un panel plano de silicio amorfo para control de la exactitud en el posicionamiento de laminas

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, J.; Gonzalez, V.; Gimeno, J.; Dolores, V. de los; Pastor, V.; Crispin, V.; Guardino, C.

    2011-07-01

    It has established a method for measuring the position of the blades in a multi leaf collimator (MLC) used to measure dose portal imaging device (EPID) of amorphous silicon, and verified its accuracy using radiochromic films and measures water with diode Cuba, techniques perfectly well validated in our institution. This dose profiles are studied for each sheet and determine their position at the point which has 50% of the dose in the open field.

  13. SU-G-BRB-03: Assessing the Sensitivity and False Positive Rate of the Integrated Quality Monitor (IQM) Large Area Ion Chamber to MLC Positioning Errors

    Energy Technology Data Exchange (ETDEWEB)

    Boehnke, E McKenzie; DeMarco, J; Steers, J; Fraass, B [Cedars-Sinai Medical Center, Los Angeles, CA (United States)

    2016-06-15

    Purpose: To examine both the IQM’s sensitivity and false positive rate to varying MLC errors. By balancing these two characteristics, an optimal tolerance value can be derived. Methods: An un-modified SBRT Liver IMRT plan containing 7 fields was randomly selected as a representative clinical case. The active MLC positions for all fields were perturbed randomly from a square distribution of varying width (±1mm to ±5mm). These unmodified and modified plans were measured multiple times each by the IQM (a large area ion chamber mounted to a TrueBeam linac head). Measurements were analyzed relative to the initial, unmodified measurement. IQM readings are analyzed as a function of control points. In order to examine sensitivity to errors along a field’s delivery, each measured field was divided into 5 groups of control points, and the maximum error in each group was recorded. Since the plans have known errors, we compared how well the IQM is able to differentiate between unmodified and error plans. ROC curves and logistic regression were used to analyze this, independent of thresholds. Results: A likelihood-ratio Chi-square test showed that the IQM could significantly predict whether a plan had MLC errors, with the exception of the beginning and ending control points. Upon further examination, we determined there was ramp-up occurring at the beginning of delivery. Once the linac AFC was tuned, the subsequent measurements (relative to a new baseline) showed significant (p <0.005) abilities to predict MLC errors. Using the area under the curve, we show the IQM’s ability to detect errors increases with increasing MLC error (Spearman’s Rho=0.8056, p<0.0001). The optimal IQM count thresholds from the ROC curves are ±3%, ±2%, and ±7% for the beginning, middle 3, and end segments, respectively. Conclusion: The IQM has proven to be able to detect not only MLC errors, but also differences in beam tuning (ramp-up). Partially supported by the Susan Scott Foundation.

  14. Palmitate-induced ER stress increases trastuzumab sensitivity in HER2/neu-positive breast cancer cells

    International Nuclear Information System (INIS)

    Baumann, Jan; Wong, Jason; Sun, Yan; Conklin, Douglas S.

    2016-01-01

    CHOP-dependent apoptosis as well as a partial activation of the ER stress response network via XBP1 and ATF6. This response appears to be a general feature of HER2/neu-positive breast cancer cells but not cells that overexpress only HER2/neu. Exogenous palmitate reduces HER2 and HER3 protein levels without changes in phosphorylation and sensitizes HER2/neu-positive breast cancer cells to treatment with the HER2-targeted therapy trastuzumab. Several studies have shown that HER2, FASN and fatty acid synthesis are functionally linked. Exogenous palmitate exerts its toxic effects in part through inducing ER stress, reducing HER2 expression and thereby sensitizing cells to trastuzumab. These data provide further evidence that HER2 signaling and fatty acid metabolism are highly integrated processes that may be important for disease development and progression. The online version of this article (doi:10.1186/s12885-016-2611-8) contains supplementary material, which is available to authorized users

  15. HIV symptom distress and anxiety sensitivity in relation to panic, social anxiety, and depression symptoms among HIV-positive adults.

    Science.gov (United States)

    Gonzalez, Adam; Zvolensky, Michael J; Parent, Justin; Grover, Kristin W; Hickey, Michael

    2012-03-01

    Although past work has documented relations between HIV/AIDS and negative affective symptoms and disorders, empirical work has only just begun to address explanatory processes that may underlie these associations. The current investigation sought to test the main and interactive effects of HIV symptom distress and anxiety sensitivity in relation to symptoms of panic disorder (PD), social anxiety disorder (SA), and depression among people with HIV/AIDS. Participants were 164 adults with HIV/AIDS (17.1% women; mean age, 48.40) recruited from AIDS service organizations (ASOs) in Vermont/New Hampshire and New York City. The sample identified as 40.9% white/Caucasian, 31.1% black, 22.0% Hispanic, and 6.1% mixed/other; with more than half (56.7%) reporting an annual income less than or equal to $10,000. Both men and women reported unprotected sex with men as the primary route of HIV transmission (64.4% and 50%, respectively). HIV symptom distress and anxiety sensitivity (AS) were significantly positively related to PD, SA, and depression symptoms. As predicted, there was a significant interaction between HIV symptom distress and anxiety sensitivity in terms of PD and SA symptoms, but not depressive symptoms. Results suggest that anxiety sensitivity and HIV symptom distress are clinically relevant factors to consider in terms of anxiety and depression among people living with HIV/AIDS. It may be important to evaluate these factors among patients with HIV/AIDS to identify individuals who may be at a particularly high risk for anxiety and depression problems. Limitations included recruitment from ASOs, cross-sectional self-report data, and lack of a clinical diagnostic assessment.

  16. Silicon micromachined vibrating gyroscopes

    Science.gov (United States)

    Voss, Ralf

    1997-09-01

    This work gives an overview of silicon micromachined vibrating gyroscopes. Market perspectives and fields of application are pointed out. The advantage of using silicon micromachining is discussed and estimations of the desired performance, especially for automobiles are given. The general principle of vibrating gyroscopes is explained. Vibrating silicon gyroscopes can be divided into seven classes. for each class the characteristic principle is presented and examples are given. Finally a specific sensor, based on a tuning fork for automotive applications with a sensitivity of 250(mu) V/degrees is described in detail.

  17. Silicon integrated circuit process

    International Nuclear Information System (INIS)

    Lee, Jong Duck

    1985-12-01

    This book introduces the process of silicon integrated circuit. It is composed of seven parts, which are oxidation process, diffusion process, ion implantation process such as ion implantation equipment, damage, annealing and influence on manufacture of integrated circuit and device, chemical vapor deposition process like silicon Epitaxy LPCVD and PECVD, photolithography process, including a sensitizer, spin, harden bake, reflection of light and problems related process, infrared light bake, wet-etch, dry etch, special etch and problems of etching, metal process like metal process like metal-silicon connection, aluminum process, credibility of aluminum and test process.

  18. Silicon integrated circuit process

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Duck

    1985-12-15

    This book introduces the process of silicon integrated circuit. It is composed of seven parts, which are oxidation process, diffusion process, ion implantation process such as ion implantation equipment, damage, annealing and influence on manufacture of integrated circuit and device, chemical vapor deposition process like silicon Epitaxy LPCVD and PECVD, photolithography process, including a sensitizer, spin, harden bake, reflection of light and problems related process, infrared light bake, wet-etch, dry etch, special etch and problems of etching, metal process like metal process like metal-silicon connection, aluminum process, credibility of aluminum and test process.

  19. Compton scatter in germanium and its effect on imaging with gamma-ray position-sensitive detectors

    International Nuclear Information System (INIS)

    Sherman, I.S.; Strauss, M.G.; Brenner, R.

    1978-01-01

    The spatial spread due to Compton scatter in Ge was measured to study the reduction in image contrast and signal-to-noise ratio (S/N) resulting from erroneous readout in Ge position-sensitive detectors. The step response revealing this spread was obtained by scanning with a 122 keV γ-ray beam across a boundary of two sectors of a slotted coaxial Ge(Li) detector that is 40 mm diameter by 22 mm long. The derived line-spread function at 140 keV (/sup 99m/Tc) exhibits much shorter but thicker tails than those due to scatter in tissue as observed with a NaI detector through 5.5 cm of scattering material. Convolutions of rectangular profiles of voids with the Ge(Li) line-spread function show marked deterioration in contrast for voids less than 10 mm across, which in turn results in even greater deterioration of the S/N. As a result, the contrast for voids in Ge images is only 20 to 30 percent higher than that in NaI and the S/N is only comparable for equal detector areas. The degradation in image contrast due to scatter in Ge detectors can be greatly reduced by either using thin detectors (approximately 5 mm), where scatter virtually does not exist, or by using thicker detectors and rejecting scatter electronically. To reduce the effects of scatter on the S/N as well as on contrast, the erroneous position readouts must actually be corrected. A more realizable approach to achieving the ultimate potential of Ge detectors may be a scanning array of discrete detectors (not position sensitive) in which readout is not affected by scatter

  20. Silicon photomultiplier as a detector of Cherenkov photons

    International Nuclear Information System (INIS)

    Korpar, S.; Dolenec, R.; Hara, K.; Iijima, T.; Krizan, P.; Mazuka, Y.; Pestotnik, R.; Stanovnik, A.; Yamaoka, M.

    2008-01-01

    A novel photon detector-i.e. the silicon photomultiplier-whose main advantage over conventional photomultiplier tubes is the operation in high magnetic fields, has been tested as a photon detector in a proximity focusing RICH with aerogel radiator. This type of RICH counter is proposed for the upgrade of the Belle detector at the KEK B-factory. Recently produced silicon photomultipliers show less noise and have larger size, which are important issues for a large area photon detector. We measured the single photon pulse height distribution, the timing resolution and the position sensitivity for different silicon photomultipliers (Hamamatsu MPPC HC025, HC050, and HC100). The silicon photomultipliers were then used to detect Cherenkov photons emitted by cosmic ray particles in a proximity focusing aerogel RICH. Various light guides were investigated in order to increase the detection efficiency

  1. Enhanced Raman scattering in porous silicon grating.

    Science.gov (United States)

    Wang, Jiajia; Jia, Zhenhong; Lv, Changwu

    2018-03-19

    The enhancement of Raman signal on monocrystalline silicon gratings with varying groove depths and on porous silicon grating were studied for a highly sensitive surface enhanced Raman scattering (SERS) response. In the experiment conducted, porous silicon gratings were fabricated. Silver nanoparticles (Ag NPs) were then deposited on the porous silicon grating to enhance the Raman signal of the detective objects. Results show that the enhancement of Raman signal on silicon grating improved when groove depth increased. The enhanced performance of Raman signal on porous silicon grating was also further improved. The Rhodamine SERS response based on Ag NPs/ porous silicon grating substrates was enhanced relative to the SERS response on Ag NPs/ porous silicon substrates. Ag NPs / porous silicon grating SERS substrate system achieved a highly sensitive SERS response due to the coupling of various Raman enhancement factors.

  2. A broadband-sensitive upconverter La(Ga{sub 0.5}Sc{sub 0.5})O{sub 3}:Er,Ni,Nb for crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Yasuhiko, E-mail: takeda@mosk.tytlabs.co.jp; Mizuno, Shintaro; Luitel, Hom Nath; Tani, Toshihiko [Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)

    2016-01-25

    We have developed an upconverter that significantly broadens the sensitive range, to overcome the shortcoming that conventional Er{sup 3+}-doped upconverters used for crystalline silicon solar cells can utilize only a small portion of the solar spectrum at around 1.55 μm. We have designed the combination of the sensitizers and host material to utilize photons not absorbed by silicon or Er{sup 3+} ions. Ni{sup 2+} ions have been selected as the sensitizers that absorb photons in the wavelength range between the silicon absorption edge (1.1 μm) and the Er{sup 3+} absorption band and transfer the energies to the Er{sup 3+} emitters, with La(Ga,Sc)O{sub 3} as the host material. The Ga to Sc ratio has been optimized to tune the location of the Ni{sup 2+} absorption band for sufficient energy transfer. Co-doping with Nb{sup 5+} ions is needed for charge balance to introduce divalent Ni{sup 2+} ions into the trivalent Ga{sup 3+} and Sc{sup 3+} sites. In addition to 1.45–1.58 μm photons directly absorbed by the Er{sup 3+} ions, we have demonstrated upconversion of 1.1–1.35 μm photons in the Ni{sup 2+} absorption band to 0.98 μm photons, using 10% Er, 0.5% Ni, and 0.5% Nb-doped La(Ga{sub 0.5}Sc{sub 0.5})O{sub 3}. The broadband-sensitive upconverter developed here can improve conversion efficiency of crystalline silicon solar cells more notably than conventional ones.

  3. BACTERIOLOGICAL STUDY OF COAGULASE-POSITIVE AND COAGULASE-NEGATIVE STAPHYLOCOCCI IN RELATION TO METHICILLIN SENSITIVITY TESTING

    Directory of Open Access Journals (Sweden)

    Padmanabham Yalangi

    2016-10-01

    Full Text Available BACKGROUND Staphylococcus aureus has long been recognised as an important pathogen in human disease. Staphylococci infection occurs regularly in hospitalised patients and has serious consequences despite antibiotic therapy. Shortly after introduction of methicillin after clinical use Methicillin-Resistant Staphylococcus Aureus (MRSA were identified in many countries and become one of the most common causes of nosocomial infections. The aim of the study is to know the methicillin sensitivity of both coagulase-negative and coagulase-positive staphylococci isolated from various samples. MATERIALS AND METHODS 100 strains of staphylococci both coagulase positive and coagulase negative were isolated in the Department of Microbiology from various clinical samples. They were confirmed by morphology, staining methods and by using standard bacteriological procedures and biochemical reactions. Antibiotic susceptibility testing was performed by Kirby Bauer disc diffusion test. RESULTS Predominant species from pus were S. epidermidis (42.42% and from sputum S. haemolyticus (31.81% from blood S. haemolyticus (53.33%. 53% of strains produced beta-lactamase. Majority 47.22% by S. epidermidis from pus followed by S. haemolyticus 23.33% from pus. Beta-lactamase production was least from throat swab (5.55%. Out of 32 coagulase-positive staphylococci tested to methicillin 15 (46.87% were found to be sensitive, 17 (53.13% were found to be resistant. Out of 68 coagulase-negative staphylococci tested, 13 (19.11% were found to sensitive and 55 (80.88% were found to be resistant. 72% of strains were sensitive to novobiocin and 28% resistant to novobiocin. 43% showed drug resistance to 2 drugs. 14% to 3 drugs and 5 drugs. 6% of staphylococci sensitive to all the 10 drugs. CONCLUSION MRSA is a type of bacteria that is resistant to a number of widely used antibiotics. This means MRSA infections can be more difficult to treat than other bacterial infections. In recent years

  4. Simultaneous acquisition of X-ray spectra using a multi-wire, position-sensitive gas flow detector

    International Nuclear Information System (INIS)

    Beaven, Peter A.; Marmotti, Mauro; Kampmann, Reinhard; Knoth, Joachim; Schwenke, Heinrich

    2003-01-01

    A multi-wire, gas-filled position-sensitive detector has been developed for the simultaneous recording of wavelength-dispersed X-ray signals that enables X-ray fluorescence spectrometry with a limited multi-element capability in the low Z element range. Details of the modular construction of the detector are given. The detector performance was characterized using Al-Kα radiation and a variable slit system. The detector has been applied in a laboratory spectrometer equipped with an electron source and a double multilayer mirror device as the wavelength-dispersing element. Spectra from Al and Si obtained in the simultaneous acquisition mode show good agreement with calculations performed using a ray-tracing model

  5. Measurement of 18O + 10B fusion cross section and construction of a position sensitive ionization chamber

    International Nuclear Information System (INIS)

    Added, N.

    1987-01-01

    The 18 O + 10 B fusion reaction has been investigated within the bombarding energy range of 29,0 MeV lab 0 lab 0 angular range. For this purpose, a high resolution position sensitive ionization chamber has been developed and constructed. Experimental results compared to model predictions and experimental systematics found in the literature allows to reject compound nucleus limitation to the fusion cross section up to energies as high as five times the coulomb barrier. Statistical model fits to the residues elementary distributions reveal a quite difuse partial fusion cross section in the angular momentum space. Systematic analysis of fusion barrier height (V B ) and radius (R B ) for neighbouring nuclei point out the importance of the nuclear matter difuseness in the competition between the fusion and quasi-direct process. Calculations within this framework were performed. (author) [pt

  6. Use of a YAP:Ce matrix coupled to a position-sensitive photomultiplier for high resolution positron emission tomography

    International Nuclear Information System (INIS)

    Del Guerra, A.; Zavattini, G.; Notaristefani, F. de; Giganti, M.; Piffanelli, A.; Pani, R.; Turra, A.

    1996-01-01

    A new scintillation detector system has been designed for application in high resolution Positron Emission Tomography (PET). The detector is a bundle of small YAlO 3 :Ce (YAP) crystals closely packed (0.2 x 0.2 x 3.0 cm 3 ), coupled to a position sensitive photomultiplier tube (PSPMT). The preliminary results obtained for spatial resolution, time resolution, energy resolution and efficiency of two such detectors working in coincidence are presented. These are 1.2 mm for the FWHM spatial resolution, 2.0 ns for the FWHM time resolution and 20% for the FWHM energy resolution at 511 keV. The measured efficiency is (44 ± 3)% with a 150 keV threshold and (20 ± 2)% with a 300 keV threshold

  7. Spatial profile measurements of ion-confining potentials using novel position-sensitive ion-energy spectrometer arrays

    International Nuclear Information System (INIS)

    Yoshida, M.; Cho, T.; Hirata, M.; Ito, H.; Kohagura, J.; Yatsu, K.; Miyoshi, S.

    2003-01-01

    The first experimental demonstration of simultaneous measurements of temporally and spatially resolved ion-confining potentials phi c and end-loss-ion fluxes I ELA has been carried out during a single plasma discharge alone by the use of newly designed ion-energy-spectrometer arrays installed in both end regions of the GAMMA 10 tandem mirror. This position-sensitive ion-detector structure is proposed to obtain precise ion-energy spectra without any perturbations from simultaneously incident energetic electrons into the arrays. The relation between phi c and I ELA is physically interpreted in terms of Pastukhov's potential confinement theory. In particular, the importance of axisymmetric phi c formation is found for the plasma confinement

  8. Overexpression of GbWRKY1 positively regulates the Pi starvation response by alteration of auxin sensitivity in Arabidopsis.

    Science.gov (United States)

    Xu, Li; Jin, Li; Long, Lu; Liu, Linlin; He, Xin; Gao, Wei; Zhu, Longfu; Zhang, Xianlong

    2012-12-01

    Overexpression of a cotton defense-related gene GbWRKY1 in Arabidopsis resulted in modification of the root system by enhanced auxin sensitivity to positively regulate the Pi starvation response. GbWRKY1 was a cloned WRKY transcription factor from Gossypium barbadense, which was firstly identified as a defense-related gene and showed moderate similarity with AtWRKY75 from Arabidopsis thaliana. Overexpression of GbWRKY1 in Arabidopsis resulted in attenuated Pi starvation stress symptoms, including reduced accumulation of anthocyanin and impaired density of lateral roots (LR) in low Pi stress. The study also indicated that overexpression of GbWRKY1 caused plants constitutively exhibited Pi starvation response including increased development of LR, relatively high level of total P and Pi, high expression level of some high-affinity Pi transporters and phosphatases as well as enhanced accumulation of acid phosphatases activity during Pi-sufficient. It was speculated that GbWRKY1 may act as a positive regulator in the Pi starvation response as well as AtWRKY75. GbWRKY1 probably involves in the modulation of Pi homeostasis and participates in the Pi allocation and remobilization but do not accumulate more Pi in Pi-deficient condition, which was different from the fact that AtWRKY75 influenced the Pi status of the plant during Pi deprivation by increasing root surface area and accumulation of more Pi. Otherwise, further study suggested that the overexpression plants were more sensitive to auxin than wild-type and GbWRKY1 may partly influence the LPR1-dependent (low phosphate response 1) Pi starvation signaling pathway and was putatively independent of SUMO E3 ligase SIZ1 and PHR1 (phosphate starvation response 1) in response to Pi starvation.

  9. Influence of multiple sclerosis, age and degree of disability, in the position of the contrast sensitivity curve peak

    Directory of Open Access Journals (Sweden)

    A F Nunes

    2014-01-01

    Full Text Available Context: Contrast sensitivity (CS function is one of the most important tests available for evaluating visual impairment. Multiple sclerosis (MS can produce highly selective losses in visual function and psychophysical studies have demonstrated CS deficits for some spatial frequencies. Aims: This work studies the differences in CS between a group of controls and a group of MS patients, focusing on the location of the maximum sensitivity peak, shape of the curve, and determination of the most affected spatial frequencies. Materials and Methods: Using a sinusoidal stimulus the authors assessed CS function in 28 subjects with definitive relapsing remitting MS, and in 50 controls with acuities of 20/25 or better. The peaks of the CS curves were studied by fitting third degree polynomials to individual sets of data. Results: Compared with the control group, the CS function curve for MS subjects showed more deficits in extreme points (low- and high-spatial frequencies. Our results display significant CS losses, at the high-frequencies band level, in the beginning of the disease. When the disease progresses and the disabilities appear, there are greater losses at the low-frequencies band level. In average, the CS curve peaks for the MS group were shifted in relation to the control group. Conclusions: CS losses in the MS group suggest an association with ageing and disability level in the expanded disability status scale. The position of the CS function peak is influenced by MS, age, and degree of disability.

  10. Development of a highly sensitive current and position monitor with HTS squids and an HTS magnetic shield

    International Nuclear Information System (INIS)

    Watanabe, T.; Ikeda, T.; Kase, M.; Yano, Y.; Watanabe, S.; Sasaki, Y.; Kawaguchi, T.

    2005-01-01

    A highly sensitive current and position monitor with HTS (High-Temperature Superconducting) SQUIDs (Superconducting QUantum Interference Device) and an HTS magnetic shield for the measurement of the intensity of faint beams, such as a radioisotope beam, has been developed for the RIKEN RI beam factory project. The HTS magnetic shield and the HTS current sensor including the HTS SQUID are cooled by a low-vibration pulse-tube refrigerator. Both the HTS magnetic shield and the HTS current sensor were fabricated by dip-coating a thin Bi 2 -Sr 2 -Ca 2 -Cu 3 -O x (Bi-2223) layer on 99.9% MgO ceramic substrates. The HTS technology enables us to develop a system equipped with a downsized and highly sensitive current monitor. Recently, a prototype system was completed and installed in the beam transport line of the RIKEN Ring Cyclotron to measure the DC-current of high-energy heavy-ion beams. As a result, we succeeded in measuring the intensity of the 600 nA 40 Ar 17+ beam (95 MeV/u). We describe the present status of the monitor system and the results of the beam measurements. (author)

  11. Measurement and analysis of neutron flux distribution of STACY heterogeneous core by position sensitive proportional counter. Contract research

    Energy Technology Data Exchange (ETDEWEB)

    Murazaki, Minoru; Uno, Yuichi; Miyoshi, Yoshinori [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    We have measured neutron flux distribution around the core tank of STACY heterogeneous core by position sensitive proportional counter (PSPC) to develop the method to measure reactivity for subcritical systems. The neutron flux distribution data in the position accuracy of {+-}13 mm have been obtained in the range of uranium concentration of 50g/L to 210g/L both in critical and in subcritical state. The prompt neutron decay constant, {alpha}, was evaluated from the measurement data of pulsed neutron source experiments. We also calculated distribution of neutron flux and {sup 3}He reaction rates at the location of PSPC by using continuous energy Monte Carlo code MCNP. The measurement data was compared with the calculation results. As results of comparison, calculated values agreed generally with measurement data of PSPC with Cd cover in the region above half of solution height, but the difference between calculated value and measurement data was large in the region below half of solution height. On the other hand, calculated value agreed well with measurement data of PSPC without Cd cover. (author)

  12. Measurement and analysis of neutron flux distribution of STACY heterogeneous core by position sensitive proportional counter. Contract research

    CERN Document Server

    Murazaki, M; Uno, Y

    2003-01-01

    We have measured neutron flux distribution around the core tank of STACY heterogeneous core by position sensitive proportional counter (PSPC) to develop the method to measure reactivity for subcritical systems. The neutron flux distribution data in the position accuracy of +-13 mm have been obtained in the range of uranium concentration of 50g/L to 210g/L both in critical and in subcritical state. The prompt neutron decay constant, alpha, was evaluated from the measurement data of pulsed neutron source experiments. We also calculated distribution of neutron flux and sup 3 He reaction rates at the location of PSPC by using continuous energy Monte Carlo code MCNP. The measurement data was compared with the calculation results. As results of comparison, calculated values agreed generally with measurement data of PSPC with Cd cover in the region above half of solution height, but the difference between calculated value and measurement data was large in the region below half of solution height. On the other hand, ...

  13. Improved abundance sensitivity of molecular ions in positive-ion APCI MS analysis of petroleum in toluene.

    Science.gov (United States)

    Kim, Young Hwan; Kim, Sunghwan

    2010-03-01

    Positive-ion atmospheric pressure chemical ionization (APCI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analyses of petroleum sample were performed with higher sensitivity by switching the solvent composition from toluene and methanol or acetonitrile to a one-component system consisting only of toluene. In solvent blends, molecular ions were more abundant than were protonated ions with increasing percentages of toluene. In 100% toluene, the double-bond equivalence (DBE) distributions of molecular ions obtained by APCI MS for each compound class were very similar to those obtained in dopant assisted atmospheric pressure photo ionization (APPI) MS analyses. Therefore, it was concluded that charge-transfer reaction, which is important in toluene-doped APPI processes, also plays a major role in positive-ion APCI. In the DBE distributions of S(1), S(2), and SO heteroatom classes, a larger enhancement in the relative abundance of molecular ions at fairly specific DBE values was observed as the solvent was progressively switched to toluene. This enhanced abundance of molecular ions was likely dependent on molecular structure. Copyright 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

  14. Positive selection of a duplicated UV-sensitive visual pigment coincides with wing pigment evolution in Heliconius butterflies

    Science.gov (United States)

    Briscoe, Adriana D.; Bybee, Seth M.; Bernard, Gary D.; Yuan, Furong; Sison-Mangus, Marilou P.; Reed, Robert D.; Warren, Andrew D.; Llorente-Bousquets, Jorge; Chiao, Chuan-Chin

    2010-01-01

    The butterfly Heliconius erato can see from the UV to the red part of the light spectrum with color vision proven from 440 to 640 nm. Its eye is known to contain three visual pigments, rhodopsins, produced by an 11-cis-3-hydroxyretinal chromophore together with long wavelength (LWRh), blue (BRh) and UV (UVRh1) opsins. We now find that H. erato has a second UV opsin mRNA (UVRh2)—a previously undescribed duplication of this gene among Lepidoptera. To investigate its evolutionary origin, we screened eye cDNAs from 14 butterfly species in the subfamily Heliconiinae and found both copies only among Heliconius. Phylogeny-based tests of selection indicate positive selection of UVRh2 following duplication, and some of the positively selected sites correspond to vertebrate visual pigment spectral tuning residues. Epi-microspectrophotometry reveals two UV-absorbing rhodopsins in the H. erato eye with λmax = 355 nm and 398 nm. Along with the additional UV opsin, Heliconius have also evolved 3-hydroxy-DL-kynurenine (3-OHK)-based yellow wing pigments not found in close relatives. Visual models of how butterflies perceive wing color variation indicate this has resulted in an expansion of the number of distinguishable yellow colors on Heliconius wings. Functional diversification of the UV-sensitive visual pigments may help explain why the yellow wing pigments of Heliconius are so colorful in the UV range compared to the yellow pigments of close relatives lacking the UV opsin duplicate. PMID:20133601

  15. Silicon detectors

    International Nuclear Information System (INIS)

    Klanner, R.

    1984-08-01

    The status and recent progress of silicon detectors for high energy physics is reviewed. Emphasis is put on detectors with high spatial resolution and the use of silicon detectors in calorimeters. (orig.)

  16. Observations of Local Positive Low Cloud Feedback Patterns and Their Role in Internal Variability and Climate Sensitivity

    Science.gov (United States)

    Yuan, Tianle; Oreopoulos, Lazaros; Platnick, Steven E.; Meyer, Kerry

    2018-05-01

    Modeling studies have shown that cloud feedbacks are sensitive to the spatial pattern of sea surface temperature (SST) anomalies, while cloud feedbacks themselves strongly influence the magnitude of SST anomalies. Observational counterparts to such patterned interactions are still needed. Here we show that distinct large-scale patterns of SST and low-cloud cover (LCC) emerge naturally from objective analyses of observations and demonstrate their close coupling in a positive local SST-LCC feedback loop that may be important for both internal variability and climate change. The two patterns that explain the maximum amount of covariance between SST and LCC correspond to the Interdecadal Pacific Oscillation and the Atlantic Multidecadal Oscillation, leading modes of multidecadal internal variability. Spatial patterns and time series of SST and LCC anomalies associated with both modes point to a strong positive local SST-LCC feedback. In many current climate models, our analyses suggest that SST-LCC feedback strength is too weak compared to observations. Modeled local SST-LCC feedback strength affects simulated internal variability so that stronger feedback produces more intense and more realistic patterns of internal variability. To the extent that the physics of the local positive SST-LCC feedback inferred from observed climate variability applies to future greenhouse warming, we anticipate significant amount of delayed warming because of SST-LCC feedback when anthropogenic SST warming eventually overwhelm the effects of internal variability that may mute anthropogenic warming over parts of the ocean. We postulate that many climate models may be underestimating both future warming and the magnitude of modeled internal variability because of their weak SST-LCC feedback.

  17. Evaluation of moderately cooled pure NaI as a scintillator for position-sensitive PET detectors

    International Nuclear Information System (INIS)

    Wear, J.A.; Karp, J.S.; Haigh, A.T.; Freifelder, R.

    1996-01-01

    A new evaluation of pure NaI has been performed to determine if moderate cooling would lead to better performance than that of existing, activated NaI(Tl) position-sensitive detectors, particularly at high countrates. Using a freezer, an initial effort was performed to cool the crystal assembly to -90 C (183 K). At this temperature, pure NaI has a decay constant of 35 nsec, a light output which is about 20% that of room temperature NaI(Tl), and an energy resolution of 15%. For the PET applications the signal of room temperature (25 C) NaI(Tl) is normally pulse clipped, reducing the light output to 40% of the unclipped signal and yielding an energy resolution of 10.5%. Since the long decay of NaI(Tl) causes it to suffer more significantly than pure NaI from pre-pulse pileup, the difference in energy resolution between the two crystals at high countrates will be reduced. Also, a significantly shorter trigger deadtime with pure NaI will lead to a reduction in coincidence deadtime losses in PET. Computer simulations of large-area crystals operating at high countrates have been performed to quantify their trigger deadtime behavior and position resolution as a function of light output and pulse decay time. Having gained experience with the practical issues of cooling large crystals, measurements of position resolution have been performed with a NaI bar detector of similar geometry to the NaI(Tl) detectors in use in the PENN-PET scanner

  18. Photodiode array for position-sensitive detection using high X-ray flux provided by synchrotron radiation

    Science.gov (United States)

    Jucha, A.; Bonin, D.; Dartyge, E.; Flank, A. M.; Fontaine, A.; Raoux, D.

    1984-09-01

    Synchrotron radiation provides a high intensity source over a large range of wavelengths. This is the prominent quality that has laid the foundations of the EXAFS development (Extended X-ray Absorption Fine Structure). EXAFS data can be collected in different ways. A full scan requires 5 to 10 min, compared to the one-day data collection of a conventional Bremsstrahlung X-ray tube. Recently, by using the new photodiode array (R 1024 SFX) manufactured by Reticon, it has been possible to reduce the data collection time to less than 100 ms. The key elements of this new EXAFS method are a dispersive optics combined with a position sensitive detector able to work under very high flux conditions. The total aperture of 2500 μm × 25 μm for each pixel is well suited to spectroscopic applications. Besides its high dynamic range (> 10 4) and its linearity, the rapidity of the readout allows a flux of 10 9-10 10 photons/s over the 1024 sensing elements.

  19. A study of an optimal technological solution for the electronics of particle position sensitive gas detectors (multiwire proportional chambers)

    International Nuclear Information System (INIS)

    Zojceski, Z.

    1997-01-01

    This work aims at optimizing the electronics for position sensitive gas detectors. The first part is a review of proportional chamber operation principles and presents the different possibilities for the architecture of the electronics. The second part involves electronic signal processing for best signal-to-noise ratio. We present a time-variant filter based on a second order base line restorer.It allows a simple pole-zero and tail cancellation at high counting rates. Also, various interpolating algorithms for cathode strip chambers have been studied. The last part reports the development of a complete electronic system, from the preamplifiers up to the readout and control interface, for the cathode strip chambers in the focal plane of the BBS Spectrometer at KVI, Holland. The system is based on application specific D-size VXI modules. In all modules, the 16-bit ADCs and FIFO memory are followed by a Digital Signal Processor, which performs data filtering and cathode induced charge interpolation. Very good analog noise performance is obtained in a multi-processor environment. (author)

  20. Amorphous silicon ionizing particle detectors

    Science.gov (United States)

    Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

    1988-01-01

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

  1. Laboratory course on silicon sensors

    CERN Document Server

    Crescio, E; Roe, S; Rudge, A

    2003-01-01

    The laboratory course consisted of four different mini sessions, in order to give the student some hands-on experience on various aspects of silicon sensors and related integrated electronics. The four experiments were. 1. Characterisation of silicon diodes for particle detection 2. Study of noise performance of the Viking readout circuit 3. Study of the position resolution of a silicon microstrip sensor 4. Study of charge transport in silicon with a fast amplifier The data in the following were obtained during the ICFA school by the students.

  2. Sensitivity and specificity of CT colonography for the detection of colonic neoplasia after positive faecal occult blood testing: systematic review and meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Plumb, Andrew A.; Pendse, Douglas A.; Taylor, Stuart A. [University College London, Centre for Medical Imaging, London (United Kingdom); Halligan, Steve [University College London, Centre for Medical Imaging, London (United Kingdom); University College London, University College Hospital, Centre for Medical Imaging, Podium Level 2, London (United Kingdom); Mallett, Susan [University of Oxford, Department of Primary Care Health Sciences, Oxford (United Kingdom)

    2014-05-15

    CT colonography (CTC) is recommended after positive faecal occult blood testing (FOBt) when colonoscopy is incomplete or infeasible. We aimed to estimate the sensitivity and specificity of CTC for colorectal cancer and adenomatous polyps following positive FOBt via systematic review. The MEDLINE, EMBASE, AMED and Cochrane Library databases were searched for CTC studies reporting sensitivity and specificity for colorectal cancer and adenomatous polyps. Included subjects had tested FOBt-positive by guaiac or immunochemical methods. Per-patient detection rates were summarized via forest plots. Meta-analysis of sensitivity and specificity was conducted using a bivariate random effects model and the average operating point calculated. Of 538 articles considered, 5 met inclusion criteria, describing results from 622 patients. Research study quality was good. CTC had a high per-patient average sensitivity of 88.8 % (95 % CI 83.6 to 92.5 %) for ≥6 mm adenomas or colorectal cancer, with low between-study heterogeneity. Specificity was both more heterogeneous and lower, at an average of 75.4 % (95 % CI 58.6 to 86.8 %). Few studies have investigated CTC in FOBt-positive individuals. CTC is sensitive at a ≥6 mm threshold but specificity is lower and variable. Despite the limited data, these results suggest that CTC may adequately substitute for colonoscopy when the latter is undesirable. (orig.)

  3. Sensitivity and specificity of CT colonography for the detection of colonic neoplasia after positive faecal occult blood testing: systematic review and meta-analysis

    International Nuclear Information System (INIS)

    Plumb, Andrew A.; Pendse, Douglas A.; Taylor, Stuart A.; Halligan, Steve; Mallett, Susan

    2014-01-01

    CT colonography (CTC) is recommended after positive faecal occult blood testing (FOBt) when colonoscopy is incomplete or infeasible. We aimed to estimate the sensitivity and specificity of CTC for colorectal cancer and adenomatous polyps following positive FOBt via systematic review. The MEDLINE, EMBASE, AMED and Cochrane Library databases were searched for CTC studies reporting sensitivity and specificity for colorectal cancer and adenomatous polyps. Included subjects had tested FOBt-positive by guaiac or immunochemical methods. Per-patient detection rates were summarized via forest plots. Meta-analysis of sensitivity and specificity was conducted using a bivariate random effects model and the average operating point calculated. Of 538 articles considered, 5 met inclusion criteria, describing results from 622 patients. Research study quality was good. CTC had a high per-patient average sensitivity of 88.8 % (95 % CI 83.6 to 92.5 %) for ≥6 mm adenomas or colorectal cancer, with low between-study heterogeneity. Specificity was both more heterogeneous and lower, at an average of 75.4 % (95 % CI 58.6 to 86.8 %). Few studies have investigated CTC in FOBt-positive individuals. CTC is sensitive at a ≥6 mm threshold but specificity is lower and variable. Despite the limited data, these results suggest that CTC may adequately substitute for colonoscopy when the latter is undesirable. (orig.)

  4. A high count rate one-dimensional position sensitive detector and a data acquisition system for time resolved X-ray scattering studies

    International Nuclear Information System (INIS)

    Pernot, P.

    1982-01-01

    A curved multiwire proportional drift chamber has been built as a general purpose instrument for X-ray scattering and X-ray diffraction experiments with synchrotron radiation. This parallaxe-free one-dimensional linear position sensitive detector has a parallel readout with a double hit logic. The data acquisition system, installed as a part of the D11 camera at LURE-DCI, is designed to perform time slicing and cyclic experiments; it has been used with either the fast multiwire chamber or a standard position sensitive detector with delay line readout [fr

  5. The noise analysis and optimum filtering techniques for a two-dimensional position sensitive orthogonal strip gamma ray detector employing resistive charge division

    International Nuclear Information System (INIS)

    Gerber, M.S.; Muller, D.W.

    1976-01-01

    The analysis of an orthogonal strip, two-dimensional position sensitive high purity germanium gamma ray detector is discussed. Position sensitivity is obtained by connecting each electrode strip on the detector to a resistor network. Charge, entering the network, divides in relation to the resistance between its entry point and the virtual earth points of the charge sensitive preamplifiers located at the end of each resistor network. The difference of the voltage pulses at the output of each preamplifier is proportional to the position at which the charge entered the resistor network and the sum of the pulse is proportional to the energy of the detected gamma ray. The analysis and spatial noise resolution is presented for this type of position sensitive detector. The results of the analysis show that the position resolution is proportional to the square root of the filter amplifier's output pulse time constant and that for energy measurement the resolution is maximized at the filter amplifier's noise corner time constant. The design of the electronic noise filtering system for the prototype gamma ray camera was based on the mathematical energy and spatial resolution equations. For the spatial channel a Gaussian trapezoidal filtering system was developed. Gaussian filtering was used for the energy channel. The detector noise model was verified by taking rms noise measurements of the filtered energy and spatial pulses from resistive readout charge dividing detectors. These measurements were within 10% of theory. (Auth.)

  6. A position sensitive detector using a NaI(Tl)/photomultiplier tube combination for the energy range 200 keV to 10 MeV

    International Nuclear Information System (INIS)

    Court, A.J.; Dean, A.J.; Yearworth, M.; Younis, F.; Chiappetti, L.; Perotti, F.; Villa, G.; Ubertini, P.; La Padula, C.

    1988-01-01

    The performance of the position sensitive detector for the ZEBRA low energy gamma-ray imaging telescope is described. The detector consists of 9 position sensitive NaI(Tl) elements each 5.8x5.0x56.0 cm viewed at either end of the long axis by 2 in. photomultiplier tubes. The total active area is 2470 cm 2 with an average positional resolution of 2.1 cm and energy resolution of 15% FWHM at 661.6 keV. The method of flight calibration is described together with the provision within the on-board electronics to correct for sources of error in the calculation of event energy loss and position. The results presented are obtained from the calibration phase of the ZEBRA telescope project. (orig.)

  7. MR imaging of silicone breast implants: evaluation of prospective and retrospective interpretations and interobserver agreement.

    Science.gov (United States)

    Quinn, S F; Neubauer, N M; Sheley, R C; Demlow, T A; Szumowski, J

    1996-01-01

    MR imaging was used to evaluate the integrity of silicone breast implants in 54 women with 108 implants. MR images were interpreted by relatively inexperienced readers who tried to reproduce the experiences reported in the literature. The study examines the interobserver agreement using different diagnostic signs and the influence of experience on interpretation errors. Prospective and retrospective interpretations were compared with surgical findings at the time of explanation. Diagnostic indicators, including the linguine sign, the inverted tear drop sign, the C sign, water droplets mixed with silicone, and extracapsular globules of silicone, were evaluated for diagnostic efficacy and interobserver agreement. The prospective sensitivity and specificity were 87% and 78%, respectively. With the retrospective interpretations, the sensitivity and specificity increased to 93% and 92%, respectively. Most of the prospective false-positive interpretations were due to misinterpreting radial folds as signs of implant rupture. Six implants interpreted retrospectively as false positives had gross amounts of silicone around the implants at surgery but there were no obvious rents in the implant shells. There was fair to excellent interobserver agreement with the individual diagnostic signs except for extracapsular globules of silicone. All of the signs had specificities of greater than 90%. The sensitivities of the individual signs were less than the overall retrospective sensitivity. With experience, the sensitivity improved from 87% to 93% and the specificity improved from 78% to 92%. This study helps substantiate the use of diagnostic signs used by other authors to detect silicone loss from breast implants by MR imaging; however, questions remain as to the clinical role of MR imaging in evaluating implants for silicone loss.

  8. Charge Collection Efficiency Simulations of Irradiated Silicon Strip Detectors

    CERN Document Server

    Peltola, T.

    2014-01-01

    During the scheduled high luminosity upgrade of LHC, the world's largest particle physics accelerator at CERN, the position sensitive silicon detectors installed in the vertex and tracking part of the CMS experiment will face more intense radiation environment than the present system was designed for. Thus, to upgrade the tracker to required performance level, comprehensive measurements and simulations studies have already been carried out. Essential information of the performance of an irradiated silicon detector is obtained by monitoring its charge collection efficiency (CCE). From the evolution of CCE with fluence, it is possible to directly observe the effect of the radiation induced defects to the ability of the detector to collect charge carriers generated by traversing minimum ionizing particles (mip). In this paper the numerically simulated CCE and CCE loss between the strips of irradiated silicon strip detectors are presented. The simulations based on Synopsys Sentaurus TCAD framework were performed ...

  9. Detection of charged particles in amorphous silicon layers

    International Nuclear Information System (INIS)

    Kaplan, S.N.; Morel, J.R.; Mulera, T.A.; Perez-Mendez, V.; Schnurmacher, G.; Street, R.A.

    1985-10-01

    The successful development of radiation detectors made from amorphous silicon could offer the possibility for relatively easy construction of large area position-sensitive detectors. We have conducted a series of measurements with prototype detectors, on signals derived from alpha particles. The measurement results are compared with simple model calculations, and projections are made of potential applications in high-energy and nuclear physics. 4 refs., 7 figs

  10. Low incidence of minor BRAF V600 mutation-positive subclones in primary and metastatic melanoma determined by sensitive and quantitative real-time PCR

    DEFF Research Database (Denmark)

    Kielsgaard Kristensen, Thomas; Clemmensen, Ole; Hoejberg, Lise

    2013-01-01

    BRAF V600 mutation is an important biological marker for therapeutic guidance in melanoma, where mutation-positive cases are candidates for therapy targeting mutant B-Raf. Recent studies showing intratumor variation in BRAF mutation status have caused concern that sensitive mutation analysis can ...

  11. Performance of a position sensitive Si(Li) x-ray detector dedicated to Compton polarimetry of stored and trapped highly-charged ions

    International Nuclear Information System (INIS)

    Weber, G; Braeuning, H; Hess, S; Maertin, R; Spillmann, U; Stoehlker, Th

    2010-01-01

    We report on a novel two-dimensional position sensitive Si(Li) detector dedicated to Compton polarimetry of x-ray radiation arising from highly-charged ions. The performance of the detector system was evaluated in ion-atom collision experiments at the ESR storage ringe at GSI, Darmstadt. Based on the data obtained, the polarimeter efficiency is estimated in this work.

  12. Effect of refraction index and thickness of the light guide in the position-sensitive gamma-ray detector using compact PS-PMTs

    International Nuclear Information System (INIS)

    Inoue, K.; Saito, H.; Nagashima, Y.; Hyodo, T.; Nagai, Y.; Muramatsu, S.; Nagai, S.

    2000-01-01

    We constructed a position-sensitive gamma-ray detector consisting of an array of BGO scintillators, a light guide and compact PS-PMTs. The effects of refractive index and thickness of the light guide of a glass plate on the detector performance were investigated. A light guide with higher refractive index and smaller thickness is found better for a good spatial resolution.

  13. ALICE Silicon Pixel Detector

    CERN Multimedia

    Manzari, V

    2013-01-01

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

  14. Impact of variation in the BDNF gene on social stress sensitivity and the buffering impact of positive emotions: replication and extension of a gene-environment interaction.

    Science.gov (United States)

    van Winkel, Mark; Peeters, Frenk; van Winkel, Ruud; Kenis, Gunter; Collip, Dina; Geschwind, Nicole; Jacobs, Nele; Derom, Catherine; Thiery, Evert; van Os, Jim; Myin-Germeys, Inez; Wichers, Marieke

    2014-06-01

    A previous study reported that social stress sensitivity is moderated by the brain-derived-neurotrophic-factor(Val66Met) (BDNF rs6265) genotype. Additionally, positive emotions partially neutralize this moderating effect. The current study aimed to: (i) replicate in a new independent sample of subjects with residual depressive symptoms the moderating effect of BDNF(Val66Met) genotype on social stress sensitivity, (ii) replicate the neutralizing impact of positive emotions, (iii) extend these analyses to other variations in the BDNF gene in the new independent sample and the original sample of non-depressed individuals. Previous findings were replicated in an experience sampling method (ESM) study. Negative Affect (NA) responses to social stress were stronger in "Val/Met" carriers of BDNF(Val66Met) compared to "Val/Val" carriers. Positive emotions neutralized the moderating effect of BDNF(Val66Met) genotype on social stress sensitivity in a dose-response fashion. Finally, two of four additional BDNF SNPs (rs11030101, rs2049046) showed similar moderating effects on social stress-sensitivity across both samples. The neutralizing effect of positive emotions on the moderating effects of these two additional SNPs was found in one sample. In conclusion, ESM has important advantages in gene-environment (GxE) research and may attribute to more consistent findings in future GxE research. This study shows how the impact of BDNF genetic variation on depressive symptoms may be explained by its impact on subtle daily life responses to social stress. Further, it shows that the generation of positive affect (PA) can buffer social stress sensitivity and partially undo the genetic susceptibility. Copyright © 2014 Elsevier B.V. and ECNP. All rights reserved.

  15. Proteasome inhibitor MG132 sensitizes HPV-positive human cervical cancer cells to rhTRAIL-induced apoptosis

    NARCIS (Netherlands)

    Hougardy, BMT; Maduro, JH; van der Zee, AGJ; de Groot, DJA; van den Heuvel, FAJ; de Vries, EGE; de Jong, S

    2006-01-01

    In cervical carcinogenesis, the p53 tumor suppressor pathway is disrupted by HPV (human papilloma virus) E6 oncogene expression. E6 targets p53 for rapid proteasome-mediated degradation. We therefore investigated whether proteasome inhibition by MG132 could restore wild-type p53 levels and sensitize

  16. Reflexive Positioning in a Politically Sensitive Situation: Dealing with the Threats of Researching the West Bank Settler Experience

    Science.gov (United States)

    Possick, Chaya

    2009-01-01

    For the past 7 years, the author has conducted qualitative research projects revolving around the experiences of West Bank settlers. The political situation in Israel in general, and the West Bank in particular, has undergone rapid and dramatic political, military, and social changes during this period. In highly politically sensitive situations…

  17. A Highly Sensitive Porous Silicon (P-Si)-Based Human Kallikrein 2 (hK2) Immunoassay Platform toward Accurate Diagnosis of Prostate Cancer.

    Science.gov (United States)

    Lee, Sang Wook; Hosokawa, Kazuo; Kim, Soyoun; Jeong, Ok Chan; Lilja, Hans; Laurell, Thomas; Maeda, Mizuo

    2015-05-22

    Levels of total human kallikrein 2 (hK2), a protein involved the pathology of prostate cancer (PCa), could be used as a biomarker to aid in the diagnosis of this disease. In this study, we report on a porous silicon antibody immunoassay platform for the detection of serum levels of total hK2. The surface of porous silicon has a 3-dimensional macro- and nanoporous structure, which offers a large binding capacity for capturing probe molecules. The tailored pore size of the porous silicon also allows efficient immobilization of antibodies by surface adsorption, and does not require chemical immobilization. Monoclonal hK2 capture antibody (6B7) was dispensed onto P-Si chip using a piezoelectric dispenser. In total 13 × 13 arrays (169 spots) were spotted on the chip with its single spot volume of 300 pL. For an optimization of capture antibody condition, we firstly performed an immunoassay of the P-Si microarray under a titration series of hK2 in pure buffer (PBS) at three different antibody densities (75, 100 and 145 µg/mL). The best performance of the microarray platform was seen at 100 µg/mL of the capture antibody concentration (LOD was 100 fg/mL). The platform then was subsequently evaluated for a titration series of serum-spiked hK2 samples. The developed platform utilizes only 15 µL of serum per test and the total assay time is about 3 h, including immobilization of the capture antibody. The detection limit of the hK2 assay was 100 fg/mL in PBS buffer and 1 pg/mL in serum with a dynamic range of 106 (10(-4) to 10(2) ng/mL).

  18. First charge collection and position-precision data on the medium-resistivity silicon strip detectors before and after neutron irradiation up to 2x10 sup 1 sup 4 n/cm sup 2

    CERN Document Server

    Li Zheng; Eremin, V; Li, C J; Verbitskaya, E

    1999-01-01

    Test strip detectors of 125 mu m, 500 mu m, and 1 mm pitches with about 1 cm sup 2 areas have been made on medium-resistivity silicon wafers (1.3 and 2.7 k OMEGA cm). Detectors of 500 mu m pitch have been tested for charge collection and position precision before and after neutron irradiation (up to 2x10 sup 1 sup 4 n/cm sup 2) using 820 and 1030 nm laser lights with different beam-spot sizes. It has been found that for a bias of 250 V a strip detector made of 1.3 k OMEGA cm (300 mu m thick) can be fully depleted before and after an irradiation of 2x10 sup 1 sup 4 n/cm sup 2. For a 500 mu m pitch strip detector made of 2.7 k OMEGA cm tested with an 1030 nm laser light with 200 mu m spot size, the position reconstruction error is about 14 mu m before irradiation, and 17 mu m after about 1.7x10 sup 1 sup 3 n/cm sup 2 irradiation. We demonstrated in this work that medium resistivity silicon strip detectors can work just as well as the traditional high-resistivity ones, but with higher radiation tolerance. We als...

  19. First charge collection and position-precision data on the medium-resistivity silicon strip detectors before and after neutron irradiation up to 2x1014 n/cm2

    International Nuclear Information System (INIS)

    Li Zheng; Dezillie, B.; Eremin, V.; Li, C.J.; Verbitskaya, E.

    1999-01-01

    Test strip detectors of 125 μm, 500 μm, and 1 mm pitches with about 1 cm 2 areas have been made on medium-resistivity silicon wafers (1.3 and 2.7 kΩ cm). Detectors of 500 μm pitch have been tested for charge collection and position precision before and after neutron irradiation (up to 2x10 14 n/cm 2 ) using 820 and 1030 nm laser lights with different beam-spot sizes. It has been found that for a bias of 250 V a strip detector made of 1.3 kΩ cm (300 μm thick) can be fully depleted before and after an irradiation of 2x10 14 n/cm 2 . For a 500 μm pitch strip detector made of 2.7 kΩ cm tested with an 1030 nm laser light with 200 μm spot size, the position reconstruction error is about 14 μm before irradiation, and 17 μm after about 1.7x10 13 n/cm 2 irradiation. We demonstrated in this work that medium resistivity silicon strip detectors can work just as well as the traditional high-resistivity ones, but with higher radiation tolerance. We also tested charge sharing and position reconstruction using a 1030 nm wavelength (300 μm absorption length in Si at RT) laser, which provides a simulation of MIP particles in high-physics experiments in terms of charge collection and position reconstruction

  20. Silicon-micromachined microchannel plates

    CERN Document Server

    Beetz, C P; Steinbeck, J; Lemieux, B; Winn, D R

    2000-01-01

    Microchannel plates (MCP) fabricated from standard silicon wafer substrates using a novel silicon micromachining process, together with standard silicon photolithographic process steps, are described. The resulting SiMCP microchannels have dimensions of approx 0.5 to approx 25 mu m, with aspect ratios up to 300, and have the dimensional precision and absence of interstitial defects characteristic of photolithographic processing, compatible with positional matching to silicon electronics readouts. The open channel areal fraction and detection efficiency may exceed 90% on plates up to 300 mm in diameter. The resulting silicon substrates can be converted entirely to amorphous quartz (qMCP). The strip resistance and secondary emission are developed by controlled depositions of thin films, at temperatures up to 1200 deg. C, also compatible with high-temperature brazing, and can be essentially hydrogen, water and radionuclide-free. Novel secondary emitters and cesiated photocathodes can be high-temperature deposite...

  1. Characterization of X3 Silicon Detectors for the ELISSA Array at ELI-NP

    Science.gov (United States)

    Chesnevskaya, S.; Balabanski, D. L.; Choudhury, D.; Cognata, M. La; Constantin, P.; Filipescu, D. M.; Ghita, D. G.; Guardo, G. L.; Lattuada, D.; Matei, C.; Rotaru, A.; Spitaleri, C.; State, A.; Xu, Y.

    2018-01-01

    Position-sensitive silicon strip detectors represent one of the best solutions for the detection of charged particles as they provide good energy and position resolution over a large range of energies. A silicon array coupled with the gamma beams at the ELI-NP facility would allow measuring photodissociation reactions of interest for Big Bang Nucleosynthesis and on heavy nuclei intervening in the p-process. Forty X3 detectors for our ELISSA (ELI-NP Silicon Strip Detectors Array) project have been recently purchased and tested. We investigated several specifications, such as leakage currents, depletion voltage, and detector stability under vacuum. The energy and position resolution, and ballistic deficit were measured and analyzed. This paper presents the main results of our extensive testing. The measured energy resolution for the X3 detectors is better than results published for similar arrays (ANASEN or ORRUBA).

  2. Neutral vs positive oral contrast in diagnosing acute appendicitis with contrast-enhanced CT: sensitivity, specificity, reader confidence and interpretation time

    Science.gov (United States)

    Naeger, D M; Chang, S D; Kolli, P; Shah, V; Huang, W; Thoeni, R F

    2011-01-01

    Objective The study compared the sensitivity, specificity, confidence and interpretation time of readers of differing experience in diagnosing acute appendicitis with contrast-enhanced CT using neutral vs positive oral contrast agents. Methods Contrast-enhanced CT for right lower quadrant or right flank pain was performed in 200 patients with neutral and 200 with positive oral contrast including 199 with proven acute appendicitis and 201 with other diagnoses. Test set disease prevalence was 50%. Two experienced gastrointestinal radiologists, one fellow and two first-year residents blindly assessed all studies for appendicitis (2000 readings) and assigned confidence scores (1=poor to 4=excellent). Receiver operating characteristic (ROC) curves were generated. Total interpretation time was recorded. Each reader's interpretation with the two agents was compared using standard statistical methods. Results Average reader sensitivity was found to be 96% (range 91–99%) with positive and 95% (89–98%) with neutral oral contrast; specificity was 96% (92–98%) and 94% (90–97%). For each reader, no statistically significant difference was found between the two agents (sensitivities p-values >0.6; specificities p-values>0.08), in the area under the ROC curve (range 0.95–0.99) or in average interpretation times. In cases without appendicitis, positive oral contrast demonstrated improved appendix identification (average 90% vs 78%) and higher confidence scores for three readers. Average interpretation times showed no statistically significant differences between the agents. Conclusion Neutral vs positive oral contrast does not affect the accuracy of contrast-enhanced CT for diagnosing acute appendicitis. Although positive oral contrast might help to identify normal appendices, we continue to use neutral oral contrast given its other potential benefits. PMID:20959365

  3. Sensitivity of the corneal-plane refractive compensation to change in power and axial position of an intraocular lens

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2009-12-01

    Full Text Available If an intraocular lens is displaced or if its power is changed what are the consequences for the refractive compensation of the eye?  Gaussian optics is used to obtain explicit formulae for the sensitivityof the corneal-plane refractive compensation (also called the refraction, refractive state, etc to change in power and axial displacement of a thin intraocular lens implanted in a simple eye.  In particular, for a pseudophakic Gullstrand simplified eye with intraocular lens placed 5 mm behind the cornea the sensitivity to errors in the power of the intraocular lens is about  71 . 0 − 71 for an intraocular lens of power   for an intraocular lens of power 20 D, that is, the refractive compensation decreases by about 0.71 dioptres per dioptre increase in the power of the intraocular lens.  More generally the sensitivity is approximately  ( m   0037 . 0 63 . 0 F − − 0.63 ( 003 . 0 63 . 0 − − (0.0037mF where FI is the power of the intraocular lens.  Also for Gullstrand’s simplified eye the sensitivity of refractive compensation to axial displacement of the intraocular lens is approximately linear in FI about  (64D FI, in fact.  That is, for each dioptre of the power of the intraocular lens the refractive compensation increases by about 0.064 dioptres per millimetre of axial displacement towards the retina. 

  4. Semiautomatic imputation of activity travel diaries : use of global positioning system traces, prompted recall, and context-sensitive learning algorithms

    NARCIS (Netherlands)

    Moiseeva, A.; Jessurun, J.; Timmermans, H.J.P.

    2010-01-01

    The new generation of dynamic activity-based models requires multiday or multiweek activity-travel data. Global Positioning System (GPS) tracers may be a powerful technology to collect such data, but previous applications of this technology to collect data of full activity travel patterns (not just

  5. Identification of hazelnut major allergens in sensitive patients with positive double-blind, placebo-controlled food challenge results

    DEFF Research Database (Denmark)

    Pastorello, Elide A; Vieths, Stefan; Pravettoni, Valerio

    2002-01-01

    The hazelnut major allergens identified to date are an 18-kd protein homologous to Bet v 1 and a 14-kd allergen homologous to Bet v 2. No studies have reported hazelnut allergens recognized in patients with positive double-blind, placebo-controlled food challenge (DBPCFC) results or in patients...

  6. Design and construction techniques for one-meter position sensitive proportional counters of the helical delay line type

    International Nuclear Information System (INIS)

    Orbesen, S.D.; Sherman, J.D.; Flynn, E.R.

    1976-03-01

    A description is given of the techniques involved in the construction of a one-meter long helical proportional counter which produces excellent position accuracy of 1 mm while yielding particle identification through a measurement of energy loss and total energy

  7. A position sensitive gamma-ray detector which employs photodiode and CsI (T1) crystals

    International Nuclear Information System (INIS)

    Dean, A.J.; Graham, G.; Hopkins, C.J.; Ramsden, D.; Lei, M.

    1987-01-01

    A compact CsI(Tl)/photodiode gamma-ray detector is described which is capable of locating the point of interaction of incident gamma-ray photons in the spectral region around 1 MeV. Laboratory tests are used to quantify both the spectral and positional resolutions of the detectors. Their likely application in space gamma-ray astronomy is also discussed

  8. Assessment of skin sensitization under REACH: A case report on vehicle choice in the LLNA and its crucial role preventing false positive results.

    Science.gov (United States)

    Watzek, Nico; Berger, Franz; Kolle, Susanne Noreen; Kaufmann, Tanja; Becker, Matthias; van Ravenzwaay, Bennard

    2017-04-01

    In the EU, chemicals with a production or import volume in quantities of one metric ton per year or more have to be tested for skin sensitizing properties under the REACH regulation. The murine Local Lymph Node Assay (LLNA) and its modifications are widely used to fulfil the data requirement, as it is currently considered the first-choice method for in vivo testing to cover this endpoint. This manuscript describes a case study highlighting the importance of understanding the chemistry of the test material during testing for 'skin sensitization' of MCDA (mixture of 2,4- and 2,6-diamino-methylcyclohexane) with particular focus on the vehicle used. While the BrdU-ELISA modification of the LLNA using acetone/olive oil (AOO) as vehicle revealed expectable positive results. However, the concentration control analysis unexpectedly revealed an instability of MCDA in the vehicle AOO. Further studies on the reactivity showed MCDA to rapidly react with AOO under formation of various imine structures, which might have caused the positive LLNA result. The repetition of the LLNA using propylene glycol (PG) as vehicle did not confirm the positive results of the LLNA using AOO. Finally, a classification of MCDA as skin sensitizer according to the Globally Harmonized System (GHS) was not justified. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Simulation of Transient Response of Ir-TES for Position-Sensitive TES with Waveform Domain Multiplexing

    Science.gov (United States)

    Minamikawa, Y.; Sato, H.; Mori, F.; Damayanthi, R. M. T.; Takahashi, H.; Ohno, M.

    2008-04-01

    We are developing a new x-ray microcalorimeter based on a superconducting transition edge sensor (TES) as an imaging sensor. Our measurement shows unique waveforms which we consider as an expression of thermal nonuniformity of TES films. This arises from the different thermal responses, so that response signal shapes would vary according to the position of the incident x-ray. This position dependency deteriorate the measured energy resolution, but with appropriate waveform analysis, this would be useful for imaging device. For more inspection, we have developed a simulation code which enables a dynamic simulation to obtain a transient response of the TES by finite differential method. Temperature and electric current distributions are calculated. As a result, we successfully obtained waveform signals. The calculated signal waveforms have similar characteristics to the measured signals. This simulation visualized the transition state of the device and will help to design better detector.

  10. Silicon Qubits

    Energy Technology Data Exchange (ETDEWEB)

    Ladd, Thaddeus D. [HRL Laboratories, LLC, Malibu, CA (United States); Carroll, Malcolm S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2018-02-28

    Silicon is a promising material candidate for qubits due to the combination of worldwide infrastructure in silicon microelectronics fabrication and the capability to drastically reduce decohering noise channels via chemical purification and isotopic enhancement. However, a variety of challenges in fabrication, control, and measurement leaves unclear the best strategy for fully realizing this material’s future potential. In this article, we survey three basic qubit types: those based on substitutional donors, on metal-oxide-semiconductor (MOS) structures, and on Si/SiGe heterostructures. We also discuss the multiple schema used to define and control Si qubits, which may exploit the manipulation and detection of a single electron charge, the state of a single electron spin, or the collective states of multiple spins. Far from being comprehensive, this article provides a brief orientation to the rapidly evolving field of silicon qubit technology and is intended as an approachable entry point for a researcher new to this field.

  11. First Measurements of the Performance of New Semitransparent Amorphous Silicon Sensor Prototypes

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, A.; Calvo, E.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Sobron, M.; Vila, I.; Virto, A. L.; Alberdi, J.; Arce, P.; Barcala, J. M.; Ferrando, A.; Josa, M. I.; Luque, J. M.; Molinero, A.; Navarrete, J.; Oller, J. C.; Yuste, C.

    2004-07-01

    We present first results on the performance of a new generation of semitransparent amorphous silicon position detectors having good properties such as an intrinsic position resolution better than 5{mu}m, an spatial point reconstruction precision better than 10 {mu}m, deflection angles smaller than 10{mu}rad and transmission in the visible and NIR higher than 70%. In addition the sensitive area is very large: 30x30 cm''3. (Author) 10 refs.

  12. First Measurements of the Performance of New Semitransparent Amorphous Silicon Sensor Prototypes

    International Nuclear Information System (INIS)

    Calderon, A.; Calvo, E.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Sobron, M.; Vila, I.; Virto, A. L.; Alberdi, J.; Arce, P.; Barcala, J. M.; Ferrando, A.; Josa, M. I.; Luque, J. M.; Molinero, A.; Navarrete, J.; Oller, J. C.; Yuste, C.

    2004-01-01

    We present first results on the performance of a new generation of semitransparent amorphous silicon position detectors having good properties such as an intrinsic position resolution better than 5μm, an spatial point reconstruction precision better than 10 μm, deflection angles smaller than 10μrad and transmission in the visible and NIR higher than 70%. In addition the sensitive area is very large: 30x30 cm 3 . (Author) 10 refs

  13. Enriched Boron-Doped Amorphous Selenium Based Position-Sensitive Solid-State Thermal Neutron Detector for MPACT Applications

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Krishna [Univ. of South Carolina, Columbia, SC (United States)

    2017-09-29

    High-efficiency thermal neutron detectors with compact size, low power-rating and high spatial, temporal and energy resolution are essential to execute non-proliferation and safeguard protocols. The demands of such detector are not fully covered by the current detection system such as gas proportional counters or scintillator-photomultiplier tube combinations, which are limited by their detection efficiency, stability of response, speed of operation, and physical size. Furthermore, world-wide shortage of 3He gas, required for widely used gas detection method, has further prompted to design an alternative system. Therefore, a solid-state neutron detection system without the requirement of 3He will be very desirable. To address the above technology gap, we had proposed to develop new room temperature solidstate thermal neutron detectors based on enriched boron (10B) and enriched lithium (6Li) doped amorphous Se (As- 0.52%, Cl 5 ppm) semiconductor for MPACT applications. The proposed alloy materials have been identified for its many favorable characteristics - a wide bandgap (~2.2 eV at 300 K) for room temperature operation, high glass transition temperature (tg ~ 85°C), a high thermal neutron cross-section (for boron ~ 3840 barns, for lithium ~ 940 barns, 1 barn = 10-24 cm2), low effective atomic number of Se for small gamma ray sensitivity, and high radiation tolerance due to its amorphous structure.

  14. Enriched Boron-Doped Amorphous Selenium Based Position-Sensitive Solid-State Thermal Neutron Detector for MPACT Applications

    International Nuclear Information System (INIS)

    Mandal, Krishna

    2017-01-01

    High-efficiency thermal neutron detectors with compact size, low power-rating and high spatial, temporal and energy resolution are essential to execute non-proliferation and safeguard protocols. The demands of such detector are not fully covered by the current detection system such as gas proportional counters or scintillator-photomultiplier tube combinations, which are limited by their detection efficiency, stability of response, speed of operation, and physical size. Furthermore, world-wide shortage of 3 He gas, required for widely used gas detection method, has further prompted to design an alternative system. Therefore, a solid-state neutron detection system without the requirement of 3 He will be very desirable. To address the above technology gap, we had proposed to develop new room temperature solidstate thermal neutron detectors based on enriched boron ( 10 B) and enriched lithium ( 6 Li) doped amorphous Se (As- 0.52%, Cl 5 ppm) semiconductor for MPACT applications. The proposed alloy materials have been identified for its many favorable characteristics - a wide bandgap (~2.2 eV at 300 K) for room temperature operation, high glass transition temperature (t g ~ 85°C), a high thermal neutron cross-section (for boron ~ 3840 barns, for lithium ~ 940 barns, 1 barn = 10 -24 cm 2 ), low effective atomic number of Se for small gamma ray sensitivity, and high radiation tolerance due to its amorphous structure.

  15. Low Temperature-Induced 30 (LTI30 positively regulates drought stress resistance in Arabidopsis: effect on abscisic acid sensitivity and hydrogen peroxide accumulation

    Directory of Open Access Journals (Sweden)

    Haitao eShi

    2015-10-01

    Full Text Available As a dehydrin belonging to group II late embryogenesis abundant protein (LEA family, Arabidopsis Low Temperature-Induced 30 (LTI30/XERO2 has been shown to be involved in plant freezing stress resistance. However, the other roles of AtLTI30 remain unknown. In this study, we found that the expression of AtLTI30 was largely induced by drought stress and abscisic acid (ABA treatments. Thereafter, AtLTI30 knockout mutants and overexpressing plants were isolated to investigate the possible involvement of AtLTI30 in ABA and drought stress responses. AtLTI30 knockout mutants were less sensitive to ABA-mediated seed germination, while AtLTI30 overexpressing plants were more sensitive to ABA compared with wild type (WT. Consistently, the AtLTI30 knockout mutants displayed decreased drought stress resistance, while the AtLTI30 overexpressing plants showed improved drought stress resistance compared with WT, as evidenced by a higher survival rate and lower leaf water loss than WT after drought stress. Moreover, manipulation of AtLTI30 expression positively regulated the activities of catalases (CATs and endogenous proline content, as a result, negatively regulated drought stress-triggered hydrogen peroxide (H2O2 accumulation. All these results indicate that AtLTI30 is a positive regulator of plant drought stress resistance, partially through the modulation of ABA sensitivity, H2O2 and proline accumulation.

  16. Development of Radiation Hard Radiation Detectors, Differences between Czochralski Silicon and Float Zone Silicon

    CERN Document Server

    Tuominen, Eija

    2012-01-01

    The purpose of this work was to develop radiation hard silicon detectors. Radiation detectors made ofsilicon are cost effective and have excellent position resolution. Therefore, they are widely used fortrack finding and particle analysis in large high-energy physics experiments. Silicon detectors willalso be used in the CMS (Compact Muon Solenoid) experiment that is being built at the LHC (LargeHadron Collider) accelerator at CERN (European Organisation for Nuclear Research). This work wasdone in the CMS programme of Helsinki Institute of Physics (HIP).Exposure of the silicon material to particle radiation causes irreversible defects that deteriorate theperformance of the silicon detectors. In HIP CMS Programme, our approach was to improve theradiation hardness of the silicon material with increased oxygen concentration in silicon material. Westudied two different methods: diffusion oxygenation of Float Zone silicon and use of high resistivityCzochralski silicon.We processed, characterised, tested in a parti...

  17. Positive association between high-sensitivity C-reactive protein level and diabetes mellitus among US non-Hispanic black adults.

    Science.gov (United States)

    Shankar, A; Li, J

    2008-08-01

    Previous epidemiologic studies have demonstrated a positive association between serum C-reactive protein (CRP) level and diabetes mellitus. However among US race-ethnicities, the putative association between CRP and diabetes mellitus in non-Hispanic Blacks is not clear. We specifically examined the association between high-sensitivity CRP level and diabetes mellitus in a representative sample of US non-Hispanic blacks. Cross-sectional study among 1,479 National Health and Nutrition Examination Survey 1999-2002 non-Hispanic black participants aged > or = 20 years. Main outcome-of-interest was the presence of diabetes mellitus (fasting plasma glucose > or = 126 mg/dL, non-fasting plasma glucose > or = 200 mg/dL, or self-reported current use of oral hypoglycemic medication or insulin) (n=204). Higher CRP levels were positively associated with diabetes mellitus, independent of smoking, waist circumference, hypertension, and other confounders. Multivariable odds ratio (OR) [95% confidence intervals (CI)] comparing elevated CRP level (>3 mg/L) to low CRP level (diabetes mellitus appeared to be present across the full range of CRP, without any threshold effect. Higher serum high-sensitivity CRP levels are positively associated with diabetes mellitus in a sample of US non-Hispanic blacks. Inflammatory processes previously shown to be related to diabetes mellitus in other race-ethnicities may be involved in non-Hispanic blacks also.

  18. School, Supervision and Adolescent-Sensitive Clinic Care: Combination Social Protection and Reduced Unprotected Sex Among HIV-Positive Adolescents in South Africa.

    Science.gov (United States)

    Toska, Elona; Cluver, Lucie D; Boyes, Mark E; Isaacsohn, Maya; Hodes, Rebecca; Sherr, Lorraine

    2017-09-01

    Social protection can reduce HIV-risk behavior in general adolescent populations, but evidence among HIV-positive adolescents is limited. This study quantitatively tests whether social protection is associated with reduced unprotected sex among 1060 ART-eligible adolescents from 53 government facilities in South Africa. Potential social protection included nine 'cash/cash-in-kind' and 'care' provisions. Analyses tested interactive/additive effects using logistic regressions and marginal effects models, controlling for covariates. 18 % of all HIV-positive adolescents and 28 % of girls reported unprotected sex. Lower rates of unprotected sex were associated with access to school (OR 0.52 95 % CI 0.33-0.82 p = 0.005), parental supervision (OR 0.54 95 % CI 0.33-0.90 p = 0.019), and adolescent-sensitive clinic care (OR 0.43 95 % CI 0.25-0.73 p = 0.002). Gender moderated the effect of adolescent-sensitive clinic care. Combination social protection had additive effects amongst girls: without any provisions 49 % reported unprotected sex; with 1-2 provisions 13-38 %; and with all provisions 9 %. Combination social protection has the potential to promote safer sex among HIV-positive adolescents, particularly girls.

  19. Blocking the NOTCH pathway can inhibit the growth of CD133-positive A549 cells and sensitize to chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Juntao; Mao, Zhangfan; Huang, Jie; Xie, Songping; Liu, Tianshu; Mao, Zhifu, E-mail: 48151660@qq.com

    2014-02-21

    Highlights: • Notch signaling pathway members are expressed lower levels in CD133+ cells. • CD133+ cells are not as sensitive as CD133− cells to chemotherapy. • GSI could inhibit the growth of both CD133+ and CD133− cells. • Blockade of Notch signaling pathway enhanced the effect of chemotherapy with CDDP. • DAPT/CDDP co-therapy caused G2/M arrest and elimination in CD133+ cells. - Abstract: Cancer stem cells (CSCs) are believed to play an important role in tumor growth and recurrence. These cells exhibit self-renewal and proliferation properties. CSCs also exhibit significant drug resistance compared with normal tumor cells. Finding new treatments that target CSCs could significantly enhance the effect of chemotherapy and improve patient survival. Notch signaling is known to regulate the development of the lungs by controlling the cell-fate determination of normal stem cells. In this study, we isolated CSCs from the human lung adenocarcinoma cell line A549. CD133 was used as a stem cell marker for fluorescence-activated cell sorting (FACS). We compared the expression of Notch signaling in both CD133+ and CD133− cells and blocked Notch signaling using the γ-secretase inhibitor DAPT (GSI-IX). The effect of combining GSI and cisplatin (CDDP) was also examined in these two types of cells. We observed that both CD133+ and CD133− cells proliferated at similar rates, but the cells exhibited distinctive differences in cell cycle progression. Few CD133+ cells were observed in the G{sub 2}/M phase, and there were half as many cells in S phase compared with the CD133− cells. Furthermore, CD133+ cells exhibited significant resistance to chemotherapy when treated with CDDP. The expression of Notch signaling pathway members, such as Notch1, Notch2 and Hes1, was lower in CD133+ cells. GSI slightly inhibited the proliferation of both cell types and exhibited little effect on the cell cycle. The inhibitory effects of DPP on these two types of cells were

  20. Amorphous silicon radiation detectors

    Science.gov (United States)

    Street, Robert A.; Perez-Mendez, Victor; Kaplan, Selig N.

    1992-01-01

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification.

  1. Computed tomography with thermal neutrons and gaseous position sensitive detector; Tomografia computadorizada com neutrons termicos e detetor a gas sensivel a posicao

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Maria Ines Silvani

    2001-12-01

    A third generation tomographic system using a parallel thermal neutron beam and gaseous position sensitive detector has been developed along three discrete phases. At the first one, X-ray tomographic images of several objects, using a position sensitive detector designed and constructed for this purpose have been obtained. The second phase involved the conversion of that detector for thermal neutron detection, by using materials capable to convert neutrons into detectable charged particles, testing afterwards its performance in a tomographic system by evaluation the quality of the image arising from several test-objects containing materials applicable in the engineering field. High enriched {sup 3} He, replacing the argon-methane otherwise used as filling gas for the X-ray detection, as well as, a gadolinium foil, have been utilized as converters. Besides the pure enriched {sup 3} He, its mixture with argon-methane and later on with propane, have been also tested, in order to evaluate the detector efficiency and resolution. After each gas change, the overall performance of the tomographic system using the modified detector, has been analyzed through measurements of the related parameters. This was done by analyzing the images produced by test-objects containing several materials having well known attenuation coefficients for both thermal neutrons and X-rays. In order to compare the performance of the position sensitive detector as modified to detect thermal neutrons, with that of a conventional BF{sub 3} detector, additional tomographs have been conducted using the last one. The results have been compared in terms of advantages, handicaps and complementary aspects for different kinds of radiation and materials. (author)

  2. The Alignment of the CMS Silicon Tracker

    CERN Document Server

    Lampen, Pekka Tapio

    2013-01-01

    The CMS all-silicon tracker consists of 16588 modules, embedded in a solenoidal magnet providing a field of B = 3.8 T. The targeted performance requires that the alignment determines the module positions with a precision of a few micrometers. Ultimate local precision is reached by the determination of sensor curvatures, challenging the algorithms to determine about 200k parameters simultaneously, as is feasible with the Millepede II program. The main remaining challenge are global distortions that systematically bias the track parameters and thus physics measurements. They are controlled by adding further information into the alignment workflow, e.g. the mass of decaying resonances or track data taken with B = 0 T. To make use of the latter and also to integrate the determination of the Lorentz angle into the alignment procedure, the alignment framework has been extended to treat position sensitive calibration parameters. This is relevant since due to the increased LHC luminosity in 2012, the Lorentz angle ex...

  3. On the use of one-dimensional position sensitive detector for x-ray diffraction reciprocal space mapping: Data quality and limitations

    International Nuclear Information System (INIS)

    Masson, Olivier; Boulle, Alexandre; Guinebretiere, Rene; Lecomte, Andre; Dauger, Alain

    2005-01-01

    A homemade x-ray diffractometer using one-dimensional position sensitive detector (PSD) and well suited to the study of thin epitaxial layer systems is presented. It is shown how PSDs can be advantageously used to allow fast reciprocal space mapping, which is especially interesting when analyzing poor crystalline and defective layers as usually observed with oxides and ceramics films. The quality of the data collected with such a setup and the limitations of PSDs in comparison with the use of analyzer crystals are discussed. In particular, the effects of PSD on angular precision, instrument resolution and corrections that must be applied to raw data are presented

  4. The use of a position sensitive detector or of a multidetector for the measurement of pole figures by neutron time-of-flight technique

    International Nuclear Information System (INIS)

    Walther, K.

    1990-01-01

    The neutron flux of even high flux reactors is weak in comparison with the quantum flux of X-ray tubes and therefore in order to decrease the expense on measuring time more and more neutron diffractometers are equipped with position sensitive detectors or multidetectors. In this paper the peculiarities of the use of such detecting devices are discussed for the measurement of pole figures. A special arrangement of a multidetector is proposed which will allow one to scan the whole pole figure by rotating the sample about only one axis and considerably will save measuring time. 4 refs.; 5 figs

  5. Sensitivity, specificity and predictive probability values of serum agglutination test titres for the diagnosis of Salmonella Dublin culture-positive bovine abortion and stillbirth.

    Science.gov (United States)

    Sánchez-Miguel, C; Crilly, J; Grant, J; Mee, J F

    2018-06-01

    The objective of this study was to determine the diagnostic value of maternal serology for the diagnosis of Salmonella Dublin bovine abortion and stillbirth. A retrospective, unmatched, case-control study was carried out using twenty year's data (1989-2009) from bovine foetal submissions to an Irish government veterinary laboratory. Cases (n = 214) were defined as submissions with a S. Dublin culture-positive foetus from a S. Dublin unvaccinated dam where results of maternal S. Dublin serology were available. Controls (n = 415) were defined as submissions where an alternative diagnosis other than S. Dublin was made in a foetus from an S. Dublin unvaccinated dam where the results of maternal S. Dublin serology were available. A logistic regression model was fitted to the data: the dichotomous dependent variable was the S. Dublin foetal culture result, and the independent variables were the maternal serum agglutination test (SAT) titre results. Salmonella serology correctly classified 87% of S. Dublin culture-positive foetuses at a predicted probability threshold of 0.44 (cut-off at which sensitivity and specificity are at a maximum, J = 0.67). The sensitivity of the SAT at the same threshold was 73.8% (95% CI: 67.4%-79.5%), and the specificity was 93.2% (95% CI: 90.3%-95.4%). The positive and negative predictive values were 84.9% (95% CI: 79.3%-88.6%) and 87.3% (95% CI: 83.5%-91.3%), respectively. This study illustrates that the use of predicted probability values, rather than the traditional arbitrary breakpoints of negative, inconclusive and positive, increases the diagnostic value of the maternal SAT. Veterinary laboratory diagnosticians and veterinary practitioners can recover from the test results, information previously categorized, particularly from those results declared to be inconclusive. © 2017 Blackwell Verlag GmbH.

  6. Silicon photonic thermometer operating on multiple polarizations

    DEFF Research Database (Denmark)

    Guan, Xiaowei; Wang, Xiaoyan; Frandsen, Lars Hagedorn

    2016-01-01

    A silicon photonics optical thermometer simultaneously operating on the multiple polarizations is designed and experimentally demonstrated. Measured sensitivities are 86pm/°C and 48pm/°C for the transverse-electric and transverse-magnetic polarizations, respectively.......A silicon photonics optical thermometer simultaneously operating on the multiple polarizations is designed and experimentally demonstrated. Measured sensitivities are 86pm/°C and 48pm/°C for the transverse-electric and transverse-magnetic polarizations, respectively....

  7. Ultra-fast silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sadrozinski, H. F.-W., E-mail: hartmut@scipp.ucsc.edu [Santa Cruz Institute for Particle Physics, UC Santa Cruz, Santa Cruz, CA 95064 (United States); Ely, S.; Fadeyev, V.; Galloway, Z.; Ngo, J.; Parker, C.; Petersen, B.; Seiden, A.; Zatserklyaniy, A. [Santa Cruz Institute for Particle Physics, UC Santa Cruz, Santa Cruz, CA 95064 (United States); Cartiglia, N.; Marchetto, F. [INFN Torino, Torino (Italy); Bruzzi, M.; Mori, R.; Scaringella, M.; Vinattieri, A. [University of Florence, Department of Physics and Astronomy, Sesto Fiorentino, Firenze (Italy)

    2013-12-01

    We propose to develop a fast, thin silicon sensor with gain capable to concurrently measure with high precision the space (∼10 μm) and time (∼10 ps) coordinates of a particle. This will open up new application of silicon detector systems in many fields. Our analysis of detector properties indicates that it is possible to improve the timing characteristics of silicon-based tracking sensors, which already have sufficient position resolution, to achieve four-dimensional high-precision measurements. The basic sensor characteristics and the expected performance are listed, the wide field of applications are mentioned and the required R and D topics are discussed. -- Highlights: •We are proposing thin pixel silicon sensors with 10's of picoseconds time resolution. •Fast charge collection is coupled with internal charge multiplication. •The truly 4-D sensors will revolutionize imaging and particle counting in many applications.

  8. Vibrational modes of porous silicon

    International Nuclear Information System (INIS)

    Sabra, M.; Naddaf, M.

    2012-01-01

    On the basis of theoretical and experimental investigations, the origin of room temperature photoluminescence (PL) from porous silicon is found to related to chemical complexes constituted the surface, in particular, SiHx, SiOx and SiOH groups. Ab initio atomic and molecular electronic structure calculations on select siloxane compounds were used for imitation of infrared (IR) spectra of porous silicon. These are compared to the IR spectra of porous silicon recorded by using Fourier Transform Infrared Spectroscopy (FTIR). In contrast to linear siloxane, the suggested circular siloxane terminated with linear siloxane structure is found to well-imitate the experimental spectra. These results are augmented with EDX (energy dispersive x-ray spectroscopy) measurements, which showed that the increase of SiOx content in porous silicon due to rapid oxidation process results in considerable decrease in PL peak intensity and a blue shift in the peak position. (author)

  9. Simultaneous resolution of spectral and temporal properties of UV and visible fluorescence using single-photon counting with a position-sensitive detector

    International Nuclear Information System (INIS)

    Kelly, L.A.; Trunk, J.G.; Polewski, K.; Sutherland, J.C.

    1995-01-01

    A new fluorescence spectrometer has been assembled at the U9B beamline of the National Synchrotron Light Source to allow simultaneous multiwavelength and time-resolved fluorescence detection, as well as spatial imaging of the sample fluorescence. The spectrometer employs monochromatized, tunable UV and visible excitation light from a synchrotron bending magnet and an imaging spectrograph equipped with a single-photon sensitive emission detector. The detector is comprised of microchannel plates in series, with a resistive anode for encoding the position of the photon-derived current. The centroid position of the photon-induced electron cascade is derived in a position analyzer from the four signals measured at the corners of the resistive anode. Spectral information is obtained by dispersing the fluorescence spectrum across one dimension of the detector photocathode. Timing information is obtained by monitoring the voltage divider circuit at the last MCP detector. The signal from the MCP is used as a ''start'' signal to perform a time-correlated single photon counting experiment. The analog signal representing the position, and hence wavelength, is digitized concomitantly with the start/stop time difference and stored in the two-dimensional histogramming memory of a multiparameter analyzer

  10. In vitro activity of XF-73, a novel antibacterial agent, against antibiotic-sensitive and -resistant Gram-positive and Gram-negative bacterial species.

    Science.gov (United States)

    Farrell, David J; Robbins, Marion; Rhys-Williams, William; Love, William G

    2010-06-01

    The antibacterial activity of XF-73, a dicationic porphyrin drug, was investigated against a range of Gram-positive and Gram-negative bacteria with known antibiotic resistance profiles, including resistance to cell wall synthesis, protein synthesis, and DNA and RNA synthesis inhibitors as well as cell membrane-active antibiotics. Antibiotic-sensitive strains for each of the bacterial species tested were also included for comparison purposes. XF-73 was active [minimum inhibitory concentration (MIC) 0.25-4 mg/L] against all of the Gram-positive bacteria tested, irrespective of the antibiotic resistance profile of the isolates, suggesting that the mechanism of action of XF-73 is unique compared with the major antibiotic classes. Gram-negative activity was lower (MIC 1 mg/L to > 64 mg/L). Minimum bactericidal concentration data confirmed that the activity of XF-73 was bactericidal. Time-kill kinetics against healthcare-associated and community-associated meticillin-resistant Staphylococcus aureus isolates demonstrated that XF-73 was rapidly bactericidal, with > 5 log(10) kill obtained after 15 min at 2 x MIC, the earliest time point sampled. The post-antibiotic effect (PAE) for XF-73 under conditions where the PAE for vancomycin was 5.4 h. XF-73 represents a novel broad-spectrum Gram-positive antibacterial drug with potentially beneficial characteristics for the treatment and prevention of Gram-positive bacterial infections. 2010. Published by Elsevier B.V.

  11. Comparison of multi-pole shaping and delay line clipping pre-amplifiers for position sensitive NaI(Tl) detectors

    International Nuclear Information System (INIS)

    Freifelder, R.; Karp, J.S.; Wear, J.A.; Lockyer, N.S.; Newcomer, F.M.; Surti, S.; Berg, R. van

    1998-01-01

    NaI(Tl) position sensitive detectors have been used in medical imaging for many years. For PET applications without collimators, the high counting rates place severe demands on such large area detectors. The NaI(Tl) detectors in the PENN-PET scanners are read-out via photomultiplier tubes and preamplifiers. Those preamplifiers use a delay-line clipping technique to shorten the characteristic 240 ns fall time of the NaI(Tl) signal. As an alternative, the authors have investigated a pole-zero network to shorten the signal followed by a multi-pole shaper to produce a symmetric signal suitable for high counting rates. This has been compared to the current design by measuring the energy and spatial resolution of a single detector as a function of different preamplifier designs. Data were taken over a range of ADC integration times and countrates. The new design shows improved energy resolution with short integration times. Effects on spatial resolution and deadtime are reported for large position sensitive detectors at different countrates

  12. Evolutionary Analysis Predicts Sensitive Positions of MMP20 and Validates Newly- and Previously-Identified MMP20 Mutations Causing Amelogenesis Imperfecta.

    Science.gov (United States)

    Gasse, Barbara; Prasad, Megana; Delgado, Sidney; Huckert, Mathilde; Kawczynski, Marzena; Garret-Bernardin, Annelyse; Lopez-Cazaux, Serena; Bailleul-Forestier, Isabelle; Manière, Marie-Cécile; Stoetzel, Corinne; Bloch-Zupan, Agnès; Sire, Jean-Yves

    2017-01-01

    Amelogenesis imperfecta (AI) designates a group of genetic diseases characterized by a large range of enamel disorders causing important social and health problems. These defects can result from mutations in enamel matrix proteins or protease encoding genes. A range of mutations in the enamel cleavage enzyme matrix metalloproteinase-20 gene ( MMP20 ) produce enamel defects of varying severity. To address how various alterations produce a range of AI phenotypes, we performed a targeted analysis to find MMP20 mutations in French patients diagnosed with non-syndromic AI. Genomic DNA was isolated from saliva and MMP20 exons and exon-intron boundaries sequenced. We identified several homozygous or heterozygous mutations, putatively involved in the AI phenotypes. To validate missense mutations and predict sensitive positions in the MMP20 sequence, we evolutionarily compared 75 sequences extracted from the public databases using the Datamonkey webserver. These sequences were representative of mammalian lineages, covering more than 150 million years of evolution. This analysis allowed us to find 324 sensitive positions (out of the 483 MMP20 residues), pinpoint functionally important domains, and build an evolutionary chart of important conserved MMP20 regions. This is an efficient tool to identify new- and previously-identified mutations. We thus identified six functional MMP20 mutations in unrelated families, finding two novel mutated sites. The genotypes and phenotypes of these six mutations are described and compared. To date, 13 MMP20 mutations causing AI have been reported, making these genotypes and associated hypomature enamel phenotypes the most frequent in AI.

  13. Analysis of intensities of positive and negative ion species from silicon dioxide films using time-of-flight secondary ion mass spectrometry and electronegativity of fragments

    International Nuclear Information System (INIS)

    Chiba, Kiyoshi

    2010-01-01

    Intensities of positive and negative ion species emitted from thermally oxidized and plasma-enhanced chemical vapor deposited (PECVD) SiO 2 films were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and the Saha-Boltzmann equation. Intensities of positive and negative secondary ion species were normalized to those of 28 Si + and 28 Si - ions, respectively, and an effective temperature of approximately (7.2 ± 0.1) x 10 3 K of the sputtered region bombarded with pulsed 22 kV Au 3 + primary ions was determined. Intensity spectra showed polarity dependence on both n and m values of Si n O m fragments, and a slight shift to negative polarity for PECVD SiO 2 compared to thermally oxidized SiO 2 films. By dividing the intensity ratios of negative-to-positive ions for PECVD SiO 2 by those for thermally oxidized SiO 2 films to cancel statistical factors, the difference in absolute electronegativity (half the sum of ionization potential and electron affinity of fragments) between both films was obtained. An increase in electronegativity for SiO m (m = 1, 2) and Si 2 O m (m = 1-4) fragments for PECVD SiO 2 films compared to thermally oxidized films was obtained to be 0.1-0.2 Pauling units, indicating a more covalent nature of Si-O bonds for PECVD SiO 2 films compared to the thermally oxidized SiO 2 films.

  14. Silicon drift detectors, present and future prospects

    Science.gov (United States)

    Takahashi, J.; Bellwied, R.; Beuttenmuller, R.; Caines, H.; Chen, W.; Dyke, H.; Hoffmann, G. W.; Humanic, T.; Kotov, I.; Kuczewski, P.; Leonhardt, W.; Li, Z.; Lynn, D.; Minor, R.; Munhoz, M.; Ott, G.; Pandey, S. U.; Schambach, J.; Soja, R.; Sugarbaker, E.; Willson, R. M.

    2001-04-01

    Silicon drift detectors provide unambiguous two-dimensional position information for charged particle detection with a single detector layer. A large area silicon drift detector was developed for the inner tracking detector of the STAR experiment at RHIC. In this paper, we discuss the lessons learned and the future prospects of this technology.

  15. Oblique patterned etching of vertical silicon sidewalls

    Science.gov (United States)

    Bruce Burckel, D.; Finnegan, Patrick S.; David Henry, M.; Resnick, Paul J.; Jarecki, Robert L.

    2016-04-01

    A method for patterning on vertical silicon surfaces in high aspect ratio silicon topography is presented. A Faraday cage is used to direct energetic reactive ions obliquely through a patterned suspended membrane positioned over the topography. The technique is capable of forming high-fidelity pattern (100 nm) features, adding an additional fabrication capability to standard top-down fabrication approaches.

  16. Silicon Sheet Quality is Improved By Meniscus Control

    Science.gov (United States)

    Yates, D. A.; Hatch, A. E.; Goldsmith, J. M.

    1983-01-01

    Better quality silicon crystals for solar cells are possible with instrument that monitors position of meniscus as sheet of solid silicon is drawn from melt. Using information on meniscus height, instrument generates feedback signal to control melt temperature. Automatic control ensures more uniform silicon sheets.

  17. Geochemistry of silicon isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Tiping; Li, Yanhe; Gao, Jianfei; Hu, Bin [Chinese Academy of Geological Science, Beijing (China). Inst. of Mineral Resources; Jiang, Shaoyong [China Univ. of Geosciences, Wuhan (China).

    2018-04-01

    Silicon is one of the most abundant elements in the Earth and silicon isotope geochemistry is important in identifying the silicon source for various geological bodies and in studying the behavior of silicon in different geological processes. This book starts with an introduction on the development of silicon isotope geochemistry. Various analytical methods are described and compared with each other in detail. The mechanisms of silicon isotope fractionation are discussed, and silicon isotope distributions in various extraterrestrial and terrestrial reservoirs are updated. Besides, the applications of silicon isotopes in several important fields are presented.

  18. Robust approach to maximize the range and accuracy of force application in atomic force microscopes with nonlinear position-sensitive detectors

    International Nuclear Information System (INIS)

    Silva, E C C M; Vliet, K J van

    2006-01-01

    The atomic force microscope is used increasingly to investigate the mechanical properties of materials via sample displacement under an applied force. However, both the extent of forces attainable and the accuracy of those forces measurements are significantly limited by the optical lever configuration that is commonly used to infer nanoscale deflection of the cantilever. We present a robust and general approach to characterize and compensate for the nonlinearity of the position-sensitive optical device via data processing, requiring no modification of existing instrumentation. We demonstrate that application of this approach reduced the maximum systematic error on the gradient of a force-displacement response from 50% to 5%, and doubled the calibrated force application range. Finally, we outline an experimental protocol that optimizes the use of the quasi-linear range of the most commonly available optical feedback configurations and also accounts for the residual systematic error, allowing the user to benefit from the full detection range of these indirect force sensors

  19. Measurable position-sensitive wide-angle interference effects of single photons radiated by a nitrogen-vacancy center in diamond

    International Nuclear Information System (INIS)

    Sandor Varro

    2014-01-01

    Single-photon wide-angle interference phenomena have been studied theoretically for glass-diamond-oil (air) layered structures. As a single optical radiator, one NV-center has been assumed close to the upper surface of a diamond plate, and it was represented by a Hertzian dipole of arbitrary orientation. It has been shown that the far-field interference pattern (of 3/5 or 100% visibility) is sensitive to the vertical position of the NV-center, to that extent that ∼2 nm difference in distance from the upper surface of the diamond results in ∼0.01 degree shift of the pattern, which should be a measurable effect. (author)

  20. Source Apportionment of PM2.5 Mass and Optical Attenuation Over an Ecologically Sensitive Zone in Central India by Positive Matrix Factorization

    Science.gov (United States)

    Nirmalkar, J.; Raman, R. S.

    2016-12-01

    Ambient PM2.5 samples (N=366) were collected over an ecologically sensitive zone (Van Vihar National Park) in Bhopal, Central India for two years (01 January, 2012 to 31 December, 2013). Samples were collected using three co-located Mini-Vol® samplers on Teflon, Nylon, and Quartz filter substrates. The aerosol was then chemically characterized for water-soluble inorganic ions, elements, and carbon fractions (elemental carbon and organic carbon) using ion chromatography, ED-XRF, and thermal-optical EC/OC analyzer, respectively. The optical attenuation (at 370 nm and 800 nm) of PM2.5 aerosols was also determined by optical transmissometry (OT-21). The application of Positive matrix factorization (PMF) to a combination of PM2.5 mass, its ions, elements, carbon fractions, and optical attenuation and its outcomes will be discussed.

  1. Sensitivity of predictions in an effective model: Application to the chiral critical end point position in the Nambu-Jona-Lasinio model

    International Nuclear Information System (INIS)

    Biguet, Alexandre; Hansen, Hubert; Brugiere, Timothee; Costa, Pedro; Borgnat, Pierre

    2015-01-01

    The measurement of the position of the chiral critical end point (CEP) in the QCD phase diagram is under debate. While it is possible to predict its position by using effective models specifically built to reproduce some of the features of the underlying theory (QCD), the quality of the predictions (e.g., the CEP position) obtained by such effective models, depends on whether solving the model equations constitute a well- or ill-posed inverse problem. Considering these predictions as being inverse problems provides tools to evaluate if the problem is ill-conditioned, meaning that infinitesimal variations of the inputs of the model can cause comparatively large variations of the predictions. If it is ill-conditioned, it has major consequences because of finite variations that could come from experimental and/or theoretical errors. In the following, we shall apply such a reasoning on the predictions of a particular Nambu-Jona-Lasinio model within the mean field + ring approximations, with special attention to the prediction of the chiral CEP position in the (T-μ) plane. We find that the problem is ill-conditioned (i.e. very sensitive to input variations) for the T-coordinate of the CEP, whereas, it is well-posed for the μ-coordinate of the CEP. As a consequence, when the chiral condensate varies in a 10MeV range, μ CEP varies far less. As an illustration to understand how problematic this could be, we show that the main consequence when taking into account finite variation of the inputs, is that the existence of the CEP itself cannot be predicted anymore: for a deviation as low as 0.6% with respect to vacuum phenomenology (well within the estimation of the first correction to the ring approximation) the CEP may or may not exist. (orig.)

  2. Sensitivity of predictions in an effective model: Application to the chiral critical end point position in the Nambu-Jona-Lasinio model

    Energy Technology Data Exchange (ETDEWEB)

    Biguet, Alexandre; Hansen, Hubert; Brugiere, Timothee [Universite Claude Bernard de Lyon, Institut de Physique Nucleaire de Lyon, CNRS/IN2P3, Villeurbanne Cedex (France); Costa, Pedro [Universidade de Coimbra, Centro de Fisica Computacional, Departamento de Fisica, Coimbra (Portugal); Borgnat, Pierre [CNRS, l' Ecole normale superieure de Lyon, Laboratoire de Physique, Lyon Cedex 07 (France)

    2015-09-15

    The measurement of the position of the chiral critical end point (CEP) in the QCD phase diagram is under debate. While it is possible to predict its position by using effective models specifically built to reproduce some of the features of the underlying theory (QCD), the quality of the predictions (e.g., the CEP position) obtained by such effective models, depends on whether solving the model equations constitute a well- or ill-posed inverse problem. Considering these predictions as being inverse problems provides tools to evaluate if the problem is ill-conditioned, meaning that infinitesimal variations of the inputs of the model can cause comparatively large variations of the predictions. If it is ill-conditioned, it has major consequences because of finite variations that could come from experimental and/or theoretical errors. In the following, we shall apply such a reasoning on the predictions of a particular Nambu-Jona-Lasinio model within the mean field + ring approximations, with special attention to the prediction of the chiral CEP position in the (T-μ) plane. We find that the problem is ill-conditioned (i.e. very sensitive to input variations) for the T-coordinate of the CEP, whereas, it is well-posed for the μ-coordinate of the CEP. As a consequence, when the chiral condensate varies in a 10MeV range, μ {sub CEP} varies far less. As an illustration to understand how problematic this could be, we show that the main consequence when taking into account finite variation of the inputs, is that the existence of the CEP itself cannot be predicted anymore: for a deviation as low as 0.6% with respect to vacuum phenomenology (well within the estimation of the first correction to the ring approximation) the CEP may or may not exist. (orig.)

  3. Hyperfunctioning parathyroid tumours in patients with thyroid nodules. Sensitivity and positive predictive value of high-resolution ultrasonography and 99mTc-sestamibi scintigraphy.

    Science.gov (United States)

    Lumachi, F; Marzola, M C; Zucchetta, P; Tregnaghi, A; Cecchin, D; Bui, F

    2003-09-01

    A series of 112 consecutive patients with primary hyperparathyroidism who underwent both high-resolution neck ultrasonography (US) and 99mTc-sestamibi/99mTc-pertechnetate subtraction scintigraphy (SS) prior to successful parathyroidectomy was reviewed. There were 29 (25.9%) men and 83 (74.1%) women, with a median age of 58 years (range 13-78 years). Patients were divided into two groups, according to the preoperative US findings: group A (87 patients, 77.7%) without thyroid diseases, and group B (25 patients, 22.3%) with either multinodular goitre or a solitary nontoxic thyroid nodule. In group B patients partial or total thyroidectomy was also performed, according to the intraoperative findings and frozen-section examination results. Final histopathology showed 99 (88.4%) solitary parathyroid (PT) adenomas and 3 (2.7%) PT carcinomas, while 10 (8.9%) patients had a multiglandular disease. The sensitivity and positive predictive value (PPV) were (group A vs group B) 79.8% vs 70.8% (P=0.25) and 95.7% vs 94.4% (P=0.58) for US, and 83.3% vs 87.0% (P=0.47) and 95.9% vs 90.9% (P=0.32) for SS respectively. Better but similar (P=not significant) results were obtained in patients with solitary PT tumours: 81.5% vs 77.8% (US) and 85.0 vs 94.1% (SS) sensitivity; 97.1% vs 93.3% (US) and 95.8% vs 88.9% (SS) PPV. Overall, the combination of US and SS was 92.9% sensitive (group A=93.1%, group B=92.0%; P=0.55), and the PPV reached 100% in each group. In conclusion, in patients with primary hyperparathyroidism the results of both US and SS are independent of coexistent thyroid disease, especially in patients with solitary PT tumours.

  4. Evolutionary Analysis Predicts Sensitive Positions of MMP20 and Validates Newly- and Previously-Identified MMP20 Mutations Causing Amelogenesis Imperfecta

    Directory of Open Access Journals (Sweden)

    Barbara Gasse

    2017-06-01

    Full Text Available Amelogenesis imperfecta (AI designates a group of genetic diseases characterized by a large range of enamel disorders causing important social and health problems. These defects can result from mutations in enamel matrix proteins or protease encoding genes. A range of mutations in the enamel cleavage enzyme matrix metalloproteinase-20 gene (MMP20 produce enamel defects of varying severity. To address how various alterations produce a range of AI phenotypes, we performed a targeted analysis to find MMP20 mutations in French patients diagnosed with non-syndromic AI. Genomic DNA was isolated from saliva and MMP20 exons and exon-intron boundaries sequenced. We identified several homozygous or heterozygous mutations, putatively involved in the AI phenotypes. To validate missense mutations and predict sensitive positions in the MMP20 sequence, we evolutionarily compared 75 sequences extracted from the public databases using the Datamonkey webserver. These sequences were representative of mammalian lineages, covering more than 150 million years of evolution. This analysis allowed us to find 324 sensitive positions (out of the 483 MMP20 residues, pinpoint functionally important domains, and build an evolutionary chart of important conserved MMP20 regions. This is an efficient tool to identify new- and previously-identified mutations. We thus identified six functional MMP20 mutations in unrelated families, finding two novel mutated sites. The genotypes and phenotypes of these six mutations are described and compared. To date, 13 MMP20 mutations causing AI have been reported, making these genotypes and associated hypomature enamel phenotypes the most frequent in AI.

  5. Development of 2-d position-sensitive neutron detector with individual readout. Operation test and establishment of detection system by means of neutron beam

    International Nuclear Information System (INIS)

    Tanaka, Hiroki; Yamagishi, Hideshi; Nakamura, Tatsuya; Soyama, Kazuhiko; Aizawa, Kazuya

    2005-04-01

    We have been developing the 2-d position-sensitive neutron detector with individual readout as next-generation-type detector system for neutron scattering experiments using intense pulsed neutron source. The detection system is designed to fulfill the specifications required for each neutron spectrometer, such as a count rate, efficiency, neutron/gamma-ray ratio, a spatial resolution and a size, by using suitable detector heads. The fundamental and imaging performances of the developed system assembled with a Multi-wire proportional counter head were evaluated using a collimated neutron beam. The system worked stably for long hours at the 4 He gas pressure of 5 atm with a mixture of 30% C 2 H 6 (0.26 atom 3 He) at gas gain of 450. The spatial resolutions were 1.4, 1.6 mm (FWHM) for a cathode- and a back strip- direction, respectively, considering a beam size. It was also confirmed that the spatial uniformity of the detection efficiency over the whole sensitive detection area was rather good, ±8% deviation from the average with the optimum discrimination level. (author)

  6. Therapy-refractory Panton Valentine Leukocidin-positive community-acquired methicillin-sensitive Staphylococcus aureus sepsis with progressive metastatic soft tissue infection: a case report

    Directory of Open Access Journals (Sweden)

    Schefold Joerg C

    2007-12-01

    Full Text Available Abstract We report a case of fulminant multiple organ failure including the Acute Respiratory Distress Syndrome (ARDS, haemodynamic, and renal failure due to community-acquired methicillin-sensitive Panton Valentine Leukocidin (PVL positive spa-type 284 (ST121 Staphylococcus aureus septic shock. The patient's first clinical symptom was necrotizing pneumonia. Despite organism-sensitive triple antibiotic therapy with linezolid, imipenem and clindamycin from the first day of treatment, progressive abscess formation in multiple skeletal muscles was observed. As a result, repeated surgical interventions became necessary. Due to progressive soft tissue infection, the anti-microbial therapy was changed to a combination of clindamycin and daptomycin. Continued surgical and antimicrobial therapy finally led to a stabilisation of the patients' condition. The clinical course of our patient underlines the existence of a "PVL-syndrome" which is independent of in vitro Staphylococcus aureus susceptibility. The PVL-syndrome should not only be considered in patients with soft tissue or bone infection, but also in patients with pneumonia. Such a condition, which may easily be mistaken for uncomplicated pneumonia, should be treated early, aggressively and over a long period of time in order to avoid relapsing infection.

  7. Hole Injection at the Silicon/Aqueous Electrolyte Interface: A Possible Mechanism for Chemiluminescence from Porous Silicon

    NARCIS (Netherlands)

    Kooij, Ernst S.; Butter, K.; Kelly, J.J.

    1998-01-01

    The reduction mechanism of oxidizing agents at silicon and porous silicon electrodes has been investigated in relation to light emission from the porous semiconductor. Oxidizing agents with a positive redox potential are shown to inject holes into HF-pretreated silicon. However, as the degree of

  8. A deep-level transient spectroscopy study of gamma-ray irradiation on the passivation properties of silicon nitride layer on silicon

    Science.gov (United States)

    Dong, Peng; Yu, Xuegong; Ma, Yao; Xie, Meng; Li, Yun; Huang, Chunlai; Li, Mo; Dai, Gang; Zhang, Jian

    2017-08-01

    Plasma-enhanced chemical vapor deposited silicon nitride (SiNx) films are extensively used as passivation material in the solar cell industry. Such SiNx passivation layers are the most sensitive part to gamma-ray irradiation in solar cells. In this work, deep-level transient spectroscopy has been applied to analyse the influence of gamma-ray irradiation on the passivation properties of SiNx layer on silicon. It is shown that the effective carrier lifetime decreases with the irradiation dose. At the same time, the interface state density is significantly increased after irradiation, and its energy distribution is broadened and shifts deeper with respect to the conduction band edge, which makes the interface states becoming more efficient recombination centers for carriers. Besides, C-V characteristics show a progressive negative shift with increasing dose, indicating the generation of effective positive charges in SiNx films. Such positive charges are beneficial for shielding holes from the n-type silicon substrates, i. e. the field-effect passivation. However, based on the reduced carrier lifetime after irradiation, it can be inferred that the irradiation induced interface defects play a dominant role over the trapped positive charges, and therefore lead to the degradation of passivation properties of SiNx on silicon.

  9. Close up of the pick and place tool carrying a dummy silicon sensor.

    CERN Multimedia

    Bernd Surrow

    1999-01-01

    The gantry positioning head contains a vacuum pick-up system thatallows several different pick-up tools to be used. This one isdesigned to pick up the silicon sensors. The pick-up tool containsa pressure sensitive contact which can stop the motion of the machine when the tool touches a fixed object. The shiny cylinderis the end of the microscope optics of the CCD camera.

  10. Beam test results of the irradiated Silicon Drift Detector for ALICE

    OpenAIRE

    Kushpil, S.; Crescio, E.; Giubellino, P.; Idzik, M.; Kolozhvari, A.; Kushpil, V.; Martinez, M. I.; Mazza, G.; Mazzoni, A.; Meddi, F.; Nouais, D.; Petracek, V.; Piemonte, C.; Rashevsky, A.; Riccati, L.

    2005-01-01

    The Silicon Drift Detectors will equip two of the six cylindrical layers of high precision position sensitive detectors in the ITS of the ALICE experiment at LHC. In this paper we report the beam test results of a SDD irradiated with 1 GeV electrons. The aim of this test was to verify the radiation tolerance of the device under an electron fluence equivalent to twice particle fluence expected during 10 years of ALICE operation.

  11. Antihydrogen annihilation reconstruction with the ALPHA silicon detector

    CERN Document Server

    Andresen, G B; Bertsche, W; Bowe, P D; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D.R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Hayano, R S; Humphries, A J; Hydomako, R; Jonsell, S; Jorgensen, L V; Kurchaninov, L; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Sarid, E; Seif el Nasr, S; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Yamazaki, Y

    2012-01-01

    The ALPHA experiment has succeeded in trapping antihydrogen, a major milestone on the road to spectroscopic comparisons of antihydrogen with hydrogen. An annihilation vertex detector, which determines the time and position of antiproton annihilations, has been central to this achievement. This detector, an array of double-sided silicon microstrip detector modules arranged in three concentric cylindrical tiers, is sensitive to the passage of charged particles resulting from antiproton annihilation. This article describes the method used to reconstruct the annihilation location and to distinguish the annihilation signal from the cosmic ray background. Recent experimental results using this detector are outlined.

  12. Antihydrogen annihilation reconstruction with the ALPHA silicon detector

    Energy Technology Data Exchange (ETDEWEB)

    Andresen, G.B. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Ashkezari, M.D. [Department of Physics, Simon Fraser University, Burnaby, BC, Canada V5A 1S6 (Canada); Bertsche, W. [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Bowe, P.D. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Butler, E. [European Laboratory for Particle Physics, CERN, CH-1211 Geneva 23 (Switzerland); Cesar, C.L. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil); Chapman, S. [Department of Physics, University of California, Berkeley, CA 94720-7300 (United States); Charlton, M.; Deller, A.; Eriksson, S. [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Fajans, J. [Department of Physics, University of California, Berkeley, CA 94720-7300 (United States); Friesen, T. [Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada T2N 1N4 (Canada); Fujiwara, M.C. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, Canada V6T 2A3 (Canada); Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada T2N 1N4 (Canada); Gill, D.R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, Canada V6T 2A3 (Canada); Gutierrez, A. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada V6T 1Z4 (Canada); Hangst, J.S. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Hardy, W.N. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada V6T 1Z4 (Canada); Hayden, M.E. [Department of Physics, Simon Fraser University, Burnaby, BC, Canada V5A 1S6 (Canada); Hayano, R.S. [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Humphries, A.J. [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); and others

    2012-08-21

    The ALPHA experiment has succeeded in trapping antihydrogen, a major milestone on the road to spectroscopic comparisons of antihydrogen with hydrogen. An annihilation vertex detector, which determines the time and position of antiproton annihilations, has been central to this achievement. This detector, an array of double-sided silicon microstrip detector modules arranged in three concentric cylindrical tiers, is sensitive to the passage of charged particles resulting from antiproton annihilation. This article describes the method used to reconstruct the annihilation location and to distinguish the annihilation signal from the cosmic ray background. Recent experimental results using this detector are outlined.

  13. High Dynamics and Precision Optical Measurement Using a Position Sensitive Detector (PSD in Reflection-Mode: Application to 2D Object Tracking over a Smart Surface

    Directory of Open Access Journals (Sweden)

    Ioan Alexandru Ivan

    2012-12-01

    Full Text Available When related to a single and good contrast object or a laser spot, position sensing, or sensitive, detectors (PSDs have a series of advantages over the classical camera sensors, including a good positioning accuracy for a fast response time and very simple signal conditioning circuits. To test the performance of this kind of sensor for microrobotics, we have made a comparative analysis between a precise but slow video camera and a custom-made fast PSD system applied to the tracking of a diffuse-reflectivity object transported by a pneumatic microconveyor called Smart-Surface. Until now, the fast system dynamics prevented the full control of the smart surface by visual servoing, unless using a very expensive high frame rate camera. We have built and tested a custom and low cost PSD-based embedded circuit, optically connected with a camera to a single objective by means of a beam splitter. A stroboscopic light source enhanced the resolution. The obtained results showed a good linearity and a fast (over 500 frames per second response time which will enable future closed-loop control by using PSD.

  14. An apparatus for high speed measurements of small-angle x-ray scattering profiles with a linear position sensitive detector

    International Nuclear Information System (INIS)

    Hashimoto, Takeji; Suehiro, Shoji; Shibayama, Mitsuhiro; Saijo, Kenji; Kawai, Hiromichi

    1981-01-01

    An apparatus for high speed measurements of small-angle X-ray scattering (SAXS) is described. This apparatus utilizes a 12 kW rotating anode X-ray generator, a linear position sensitive proportional counter (multicathode delay line PSPC), and a two-parameter multichannel pulse height analyzer (MCA) with 12 kwords (16 bits/word) memory area available for SAXA intensity data as a function of position (scattering angles) and time slice. The two-parameter MCA is constructed within a microcomputer system, by utilizing its R/W memory for data storage, and the memory incrementing and real-time CRT display is implemented by using two direct memory access (DMA) controllers. The cycle time of the access is about 10 μs. The measuring time for SAXS profiles with this apparatus can be shortened approximately by three orders of magnitude in comparison with the measuring time with SAXS apparatuses utilizing a conventional step-scanning goniometer and a conventional X-ray tube, thus permitting time-resolved analyses of SAXS profiles. Some applications of the apparatus to dynamic SAXS measurements are presented for polymeric systems, the preliminary results of which seem to indicate the possibility of obtaining a new class of data on dynamics in structural transformation, deformation, formation and annihilation in the scale of a few tens to several hundred Angstroms. (author)

  15. Charge collection in silicon strip detectors

    International Nuclear Information System (INIS)

    Kraner, H.W.; Beuttenmuller, R.; Ludlam, T.; Hanson, A.L.; Jones, K.W.; Radeka, V.; Heijne, E.H.M.

    1982-11-01

    The use of position sensitive silicon detectors as very high resolution tracking devices in high energy physics experiments has been a subject of intense development over the past few years. Typical applications call for the detection of minimum ionizing particles with position measurement accuracy of 10 μm in each detector plane. The most straightforward detector geometry is that in which one of the collecting electrodes is subdivided into closely spaced strips, giving a high degree of segmentation in one coordinate. Each strip may be read out as a separate detection element, or, alternatively, resistive and/or capacitive coupling between adjacent strips may be exploited to interpolate the position via charge division measrurements. With readout techniques that couple several strips, the numer of readout channels can, in principle, be reduced by large factors without sacrificing the intrinsic position accuracy. The testing of individual strip properties and charge division between strips has been carried out with minimum ionizing particles or beams for the most part except in one case which used alphs particless scans. This paper describes the use of a highly collimated MeV proton beam for studies of the position sensing properties of representative one dimensional strip detectors

  16. Sensitive monitoring of monoterpene metabolites in human urine using two-step derivatisation and positive chemical ionisation-tandem mass spectrometry

    International Nuclear Information System (INIS)

    Schmidt, Lukas; Belov, Vladimir N.; Göen, Thomas

    2013-01-01

    Highlights: •Sensitive monitoring of 10 metabolites of (R)-limonene, α-pinene, and Δ 3 -carene in human urine samples. •Fast and simple sample preparation and derivatisation procedure using two-step silylation for unreactive tertiary hydroxyl groups. •Synthesis of reference substances and isotopically labelled internal standards of (R)-limonene, α-pinene, and Δ 3 -carene metabolites. •Study on (R)-limonene, α-pinene, and Δ 3 -carene metabolite background exposure of 36 occupationally unexposed volunteers. -- Abstract: A gas chromatographic–positive chemical ionisation-tandem mass spectrometric (GC–PCI-MS/MS) method for the simultaneous determination of 10 oxidative metabolites of the monoterpenoid hydrocarbons α-pinene, (R)-limonene, and Δ 3 -carene ((+)-3-carene) in human urine was developed and tested for the monoterpene biomonitoring of the general population (n = 36). The method involves enzymatic cleavage of the glucuronides followed by solid-supported liquid–liquid extraction and derivatisation using a two-step reaction with N,O-bis(trimethylsilyl)-trifluoroacetamide and N-(trimethylsilyl)imidazole. The method proved to be both sensitive and reliable with detection limits ranging from 0.1 to 0.3 μg L −1 . In contrast to the frequent and distinct quantities of (1S,2S,4R)-limonene-1,2-diol, the (1R,2R,4R)-stereoisomer could not be detected. The expected metabolite of (+)-3-carene, 3-caren-10-ol was not detected in any of the samples. All other metabolites were detected in almost all urine samples. The procedure enables for the first time the analysis of trace levels of a broad spectrum of mono- and bicyclic monoterpenoid metabolites (alcohols, diols, and carboxylic acids) in human urine. This analytical procedure is a powerful tool for population studies as well as for the discovery of human metabolism and toxicokinetics of monoterpenes

  17. Mechanistic study on lowering the sensitivity of positive atmospheric pressure photoionization mass spectrometric analyses: size-dependent reactivity of solvent clusters.

    Science.gov (United States)

    Ahmed, Arif; Choi, Cheol Ho; Kim, Sunghwan

    2015-11-15

    Understanding the mechanism of atmospheric pressure photoionization (APPI) is important for studies employing APPI liquid chromatography/mass spectrometry (LC/MS). In this study, the APPI mechanism for polyaromatic hydrocarbon (PAH) compounds dissolved in toluene and methanol or water mixture was investigated by use of MS analysis and quantum mechanical simulation. In particular, four different mechanisms that could contribute to the signal reduction were considered based on a combination of MS data and quantum mechanical calculations. The APPI mechanism is clarified by combining MS data and density functional theory (DFT) calculations. To obtain MS data, a positive-mode (+) APPI Q Exactive Orbitrap mass spectrometer was used to analyze each solution. DFT calculations were performed using the general atomic and molecular electronic structure system (GAMESS). The experimental results indicated that methanol significantly reduced the signal in (+) APPI, but no significative signal reduction was observed when water was used as a co-solvent with toluene. The signal reduction is more significant especially for molecular ions than for protonated ions. Therefore, important information about the mechanism of methanol-induced signal reduction in (+) APPI-MS can be gained due its negative impact on APPI efficiency. The size-dependent reactivity of methanol clusters ((CH3 OH)n , n = 1-8) is an important factor in determining the sensitivity of (+) APPI-MS analyses. Clusters can compete with toluene radical ions for electrons. The reactivity increases as the sizes of the methanol clusters increase and this effect can be caused by the size-dependent ionization energy of the solvent clusters. The resulting increase in cluster reactivity explains the flow rate and temperature-dependent signal reduction observed in the analytes. Based on the results presented here, minimizing the sizes of methanol clusters can improve the sensitivity of LC/(+)-APPI-MS. Copyright © 2015 John

  18. Docosapentaenoic acid and docosahexaenoic acid are positively associated with insulin sensitivity in rats fed high-fat and high-fructose diets.

    Science.gov (United States)

    Huang, Jiung-Pang; Cheng, Mei-Ling; Hung, Cheng-Yu; Wang, Chao-Hung; Hsieh, Po-Shiuan; Shiao, Ming-Shi; Chen, Jan-Kan; Li, Dai-Er; Hung, Li-Man

    2017-10-01

    The aim of the present study was to compare insulin resistance and metabolic changes using a global lipidomic approach. Rats were fed a high-fat diet (HFD) or a high-fructose diet (HFrD) for 12 weeks to induce insulin resistance (IR) syndrome. After 12 weeks feeding, physiological and biochemical parameters were examined. Insulin sensitivity and plasma metabolites were evaluated using a euglycemic-hyperinsulinemic clamp and mass spectrometry, respectively. Pearson's correlation coefficient was used to investigate the strength of correlations. Rats on both diets developed IR syndrome, characterized by hypertension, hyperlipidemia, hyperinsulinemia, impaired fasting glucose, and IR. Compared with HFrD-fed rats, non-esterified fatty acids were lower and body weight and plasma insulin levels were markedly higher in HFD-fed rats. Adiposity and plasma leptin levels were increased in both groups. However, the size of adipocytes was greater in HFD- than HFrD-fed rats. Notably, the lipidomic heat map revealed metabolites exhibiting greater differences in HFD- and HFrD-fed rats compared with controls. Plasma adrenic acid levels were higher in HFD- than HFrD-fed rats. Nevertheless, linoleic and arachidonic acid levels decreased in HFrD-fed rats compared with controls. Plasma concentrations of docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) were significantly reduced after feeding of both diets, particularly the HFrD. There was a strong positive correlation between these two fatty acids and the insulin sensitivity index. The systemic lipidomic analysis indicated that a reduction in DHA and DPA was strongly correlated with IR in rats under long-term overnutrition. These results provide a potential therapeutic target for IR and metabolic syndrome. © 2016 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

  19. Inhibition of miR-146b expression increases radioiodine-sensitivity in poorly differential thyroid carcinoma via positively regulating NIS expression

    Energy Technology Data Exchange (ETDEWEB)

    Li, Luchuan; Lv, Bin; Chen, Bo [Department of General Surgery, Shandong University Qilu Hospital, Jinan, Shandong 250012 (China); Guan, Ming [Department of General Surgery, Qihe People' s Hospital, Qihe, Shandong 251100 (China); Sun, Yongfeng [Department of General Surgery, Licheng District People' s Hospital, Jinan, Shandong 250115 (China); Li, Haipeng [Department of General Surgery, Caoxian People' s Hospital, Caoxian, Shandong 274400 (China); Zhang, Binbin; Ding, Changyuan; He, Shan [Department of General Surgery, Shandong University Qilu Hospital, Jinan, Shandong 250012 (China); Zeng, Qingdong, E-mail: qingdz0201@163.com [Department of General Surgery, Shandong University Qilu Hospital, Jinan, Shandong 250012 (China)

    2015-07-10

    Dedifferentiated thyroid carcinoma (DTC) with the loss of radioiodine uptake (RAIU) is often observed in clinical practice under radioiodine therapy, indicating the challenge for poor prognosis. MicroRNA (miRNA) has emerged as a promising therapeutic target in many diseases; yet, the role of miRNAs in RAIU has not been generally investigated. Based on recent studies about miRNA expression in papillary or follicular thyroid carcinomas, the expression profiles of several thyroid relative miRNAs were investigated in one DTC cell line, derived from normal DTC cells by radioiodine treatment. The top candidate miR-146b, with the most significant overexpression profiles in dedifferentiated cells, was picked up. Further research found that miR-146b could be negatively regulated by histone deacetylase 3 (HDAC3) in normal cells, indicating the correlation between miR-146b and Na{sup +}/I{sup −} symporter (NIS)-mediated RAIU. Fortunately, it was confirmed that miR-146b could regulate NIS expression/activity; what is more important, miR-146b interference would contribute to the recovery of radioiodine-sensitivity in dedifferentiated cells via positively regulating NIS. In the present study, it was concluded that NIS-mediated RAIU could be modulated by miR-146b; accordingly, miR-146b might serve as one of targets to enhance efficacy of radioactive therapy against poorly differential thyroid carcinoma (PDTC). - Highlights: • Significant upregulated miR-146b was picked up from thyroid relative miRNAs in DTC. • MiR-146b was negatively regulated by HDAC3 in normal thyroid carcinoma cells. • NIS activity and expression could be regulated by miR-146b in thyroid carcinoma. • MiR-146b inhibition could recover the decreased radioiodine-sensitivity of DTC cells.

  20. A combination of positive dielectrophoresis driven on-line enrichment and aptamer-fluorescent silica nanoparticle label for rapid and sensitive detection of Staphylococcus aureus.

    Science.gov (United States)

    Shangguan, Jingfang; Li, Yuhong; He, Dinggeng; He, Xiaoxiao; Wang, Kemin; Zou, Zhen; Shi, Hui

    2015-07-07

    Staphylococcus aureus (S. aureus) is an important human pathogen that causes several diseases ranging from superficial skin infections to life-threatening diseases. Here, a method combining positive dielectrophoresis (pDEP) driven on-line enrichment and aptamer-fluorescent silica nanoparticle label has been developed for the rapid and sensitive detection of S. aureus in microfluidic channels. An aptamer, having high affinity to S. aureus, is used as the molecular recognition tool and immobilized onto chloropropyl functionalized fluorescent silica nanoparticles through a click chemistry approach to obtain S. aureus aptamer-nanoparticle bioconjugates (Apt(S.aureus)/FNPs). The pDEP driven on-line enrichment technology was used for accumulating the Apt(S.aureus)/FNP labeled S. aureus. After incubating with S. aureus, the mixture of Apt(S.aureus)/FNP labeled S. aureus and Apt(S.aureus)/FNPs was directly introduced into the pDEP-based microfluidic system. By applying an AC voltage in a pDEP frequency region, the Apt(S.aureus)/FNP labelled S. aureus moved to the electrodes and accumulated in the electrode gap, while the free Apt(S.aureus)/FNPs flowed away. The signal that came from the Apt(S.aureus)/FNP labelled S. aureus in the focused detection areas was then detected. Profiting from the specificity of aptamer, signal amplification of FNP label and pDEP on-line enrichment, this assay can detect as low as 93 and 270 cfu mL(-1)S. aureus in deionized water and spiked water samples, respectively, with higher sensitivities than our previously reported Apt(S.aureus)/FNP based flow cytometry. Moreover, without the need for separation and washing steps usually required for FNP label involved bioassays, the total assay time including sample pretreatment was within 2 h.

  1. A sensitive one-step real-time PCR for detection of avian influenza viruses using a MGB probe and an internal positive control

    Directory of Open Access Journals (Sweden)

    Delogu Mauro

    2006-05-01

    Full Text Available Abstract Background Avian influenza viruses (AIVs are endemic in wild birds and their introduction and conversion to highly pathogenic avian influenza virus in domestic poultry is a cause of serious economic losses as well as a risk for potential transmission to humans. The ability to rapidly recognise AIVs in biological specimens is critical for limiting further spread of the disease in poultry. The advent of molecular methods such as real time polymerase chain reaction has allowed improvement of detection methods currently used in laboratories, although not all of these methods include an Internal Positive Control (IPC to monitor for false negative results. Therefore we developed a one-step reverse transcription real time PCR (RRT-PCR with a Minor Groove Binder (MGB probe for the detection of different subtypes of AIVs. This technique also includes an IPC. Methods RRT-PCR was developed using an improved TaqMan technology with a MGB probe to detect AI from reference viruses. Primers and probe were designed based on the matrix gene sequences from most animal and human A influenza virus subtypes. The specificity of RRT-PCR was assessed by detecting influenza A virus isolates belonging to subtypes from H1–H13 isolated in avian, human, swine and equine hosts. The analytical sensitivity of the RRT-PCR assay was determined using serial dilutions of in vitro transcribed matrix gene RNA. The use of a rodent RNA as an IPC in order not to reduce the efficiency of the assay was adopted. Results The RRT-PCR assay is capable to detect all tested influenza A viruses. The detection limit of the assay was shown to be between 5 and 50 RNA copies per reaction and the standard curve demonstrated a linear range from 5 to 5 × 108 copies as well as excellent reproducibility. The analytical sensitivity of the assay is 10–100 times higher than conventional RT-PCR. Conclusion The high sensitivity, rapidity, reproducibility and specificity of the AIV RRT-PCR with

  2. Synthesis of Si epitaxial layers from technical silicon by liquid-phase epitaxy method

    International Nuclear Information System (INIS)

    Ibragimov, Sh.I.; Saidov, A.S.; Sapaev, B.; Horvat, M.A.

    2004-01-01

    Full text: For today silicon is one of the most suitable materials because it is investigated, cheap and several its parameters are even just as good as those of connections A III B V . Disintegration of the USSR has led to the must difficult position of the industry of silicon instrument manufacture because of all industry of semiconductor silicon manufacture had generally concentrated in Ukraine. The importance of semiconductor silicon is rather great, because of, in opinion of expects, the nearest decade this material will dominate over not only on microelectronics but also in the majority of basic researches. Research of obtain of semiconductor silicon, power electronics and solar conversion, is topical interest of the science. In the work research of technological conditions of obtain and measurement of parameters of epitaxial layers obtained from technical silicon + stannum is resulted. Growth of silicon epitaxial layer with suitable parameters on thickness, cleanliness uniformity and structural perfection depends on the correct choice of condition of the growth and temperature. It is shown that in this case the growth occurring without preliminary clearing of materials (mix materials and substrates) at crystallization of epitaxial layer from technical silicon is accompanied by clearing of silicon film from majority of impurities order-of-magnitude. As starting raw material technical silicon of mark Kr.3 has been taken. By means of X-ray microanalyzer 'Jeol' JSM 5910 LV - Japan the quantitative analysis from the different points has been and from the different sides and from different points has been carried out. After corresponding chemical and mechanical processing the quantitative analysis of layer on chip has been carried out. Results of the quantitative analysis are shown. More effective clearing occurs that of the impurity atoms such as Al, P, Ca, Ti and Fe. The obtained material (epitaxial layer) has the parameters: specific resistance ρ∼0.1-4.0

  3. Porous Silicon Sensors- Elusive and Erudite

    OpenAIRE

    H. Saha, Prof.

    2017-01-01

    Porous Silicon Sensors have been fabricated and tested successfully over the last few years as humidity sensors, vapour sensors, gas sensors, piezoresistive pressure sensors and bio- sensors. In each case it has displayed remarkably sensitivity, relatively low temperature operation and ease of fabrication. Brief description of fabrication and properties of all these types of different sensors is reported in this paper. The barriers of porous silicon like contact, non- uniformity, instability ...

  4. Efficacy of the Video-feedback Intervention to promote Positive Parenting and Sensitive Discipline in Twin Families (VIPP-Twins): Study protocol for a randomized controlled trial.

    Science.gov (United States)

    Euser, Saskia; Bakermans-Kranenburg, Marian J; van den Bulk, Bianca G; Linting, Mariëlle; Damsteegt, Rani C; Vrijhof, Claudia I; van Wijk, Ilse C; Crone, Eveline A; van IJzendoorn, Marinus H

    2016-06-06

    Intervention programs with the aim of enhancing parenting quality have been found to be differentially effective in decreasing negative child outcomes such as externalizing behavioral problems, resulting in modest overall effect sizes. Here we present the protocol for a randomized controlled trial to examine the efficacy of the Video-feedback Intervention to promote Positive Parenting and Sensitive Discipline for Twin Families (VIPP-Twins) on parenting quality and children's behavioral control and social competence. In addition, we aim to test the differential susceptibility theory; we examine differential efficacy of the intervention based on genetic make-up or temperament for both parents and children. Lastly, we explore neurobiological mechanisms underlying intervention effects on children's developmental outcomes. The original VIPP-SD was adapted for use in families with twins. The VIPP-Twins consists of five biweekly sessions in which the families are visited at home, parent-child interactions are videotaped and parents receive positive feedback on selected video fragments. Families (N = 225) with a same sex twin (mean age = 3.6 years) were recruited to participate in the study. The study consists of four assessments. After two baseline assessments in year 1 and year 2, a random 40 % of the sample will receive the VIPP-Twins program. The first post-test assessment will be carried out one month after the intervention and there will be a long term follow-up assessment two years after the intervention. Measures include observational assessments of parenting and children's social competence and behavioral control, and neurobiological assessments (i.e., hormonal functioning and neural (re-)activity). Results of the study will provide insights in the efficacy of the VIPP-Twins and reveal moderators and mediators of program efficacy. Overall the randomized controlled trial is an experimental test of the differential susceptibility theory. Dutch Trial

  5. Multi-class geospatial object detection based on a position-sensitive balancing framework for high spatial resolution remote sensing imagery

    Science.gov (United States)

    Zhong, Yanfei; Han, Xiaobing; Zhang, Liangpei

    2018-04-01

    Multi-class geospatial object detection from high spatial resolution (HSR) remote sensing imagery is attracting increasing attention in a wide range of object-related civil and engineering applications. However, the distribution of objects in HSR remote sensing imagery is location-variable and complicated, and how to accurately detect the objects in HSR remote sensing imagery is a critical problem. Due to the powerful feature extraction and representation capability of deep learning, the deep learning based region proposal generation and object detection integrated framework has greatly promoted the performance of multi-class geospatial object detection for HSR remote sensing imagery. However, due to the translation caused by the convolution operation in the convolutional neural network (CNN), although the performance of the classification stage is seldom influenced, the localization accuracies of the predicted bounding boxes in the detection stage are easily influenced. The dilemma between translation-invariance in the classification stage and translation-variance in the object detection stage has not been addressed for HSR remote sensing imagery, and causes position accuracy problems for multi-class geospatial object detection with region proposal generation and object detection. In order to further improve the performance of the region proposal generation and object detection integrated framework for HSR remote sensing imagery object detection, a position-sensitive balancing (PSB) framework is proposed in this paper for multi-class geospatial object detection from HSR remote sensing imagery. The proposed PSB framework takes full advantage of the fully convolutional network (FCN), on the basis of a residual network, and adopts the PSB framework to solve the dilemma between translation-invariance in the classification stage and translation-variance in the object detection stage. In addition, a pre-training mechanism is utilized to accelerate the training procedure

  6. High-Energy 3D Calorimeter based on position-sensitive virtual Frisch-grid CdZnTe detectors for use in Gamma-ray Astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Bolotnikov, Alexey [Brookhaven National Lab. (BNL), Upton, NY (United States); De Geronimo, GianLuigi [Brookhaven National Lab. (BNL), Upton, NY (United States); Vernon, Emerson [Brookhaven National Lab. (BNL), Upton, NY (United States); Hays, Elizabeth [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Thompson, David [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); James, Ralph [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Moiseev, Alexander [Center for Research and Exploration; Technology, NASA Goddard Space Flight Center (GSFC) and Univ. of Maryland, Greenbelt, MD (United States)

    2017-08-12

    We present a concept for a calorimeter based on a novel approach of 3D position-sensitive virtual Frischgrid CZT detectors. This calorimeter aims to measure photons with energies from ~100 keV to 10 (goal 50) MeV. The expected energy resolution at 662 keV is ~1% FWHM, and the photon interaction positionmeasurement accuracy is ~1 mm in all 3 dimensions. Each CZT bar is a rectangular prism with typical cross-section of 6x6 mm2 and length of 2-4 cm. The bars are arranged in modules of 4 x 4 bars, and the modules themselves can be assembled into a larger array. The 3D virtual voxel approach solves a long-standing problem with CZT detectors associated with material imperfections that limit the performance and usefulness of relatively thick detectors (i.e., > 1 cm). Also, it allows us to relax the requirements on the quality of the crystals, maintaining good energy resolution and significantly reducing the instrument cost. Such a calorimeter can be successfully used in space telescopes that use Compton scattering of γ rays, such as AMEGO, serving as part of its calorimeter and providing the position and energy measurement for Compton-scattered photons. Also, it could provide suitable energy resolution to allow for spectroscopic measurements of γ-ray lines from nuclear decays. Another viable option is to use this calorimeter as a focal plane to conduct spectroscopic measurements of cosmic γ-ray events. In combination with a coded-aperture mask, it potentially could provide mapping of the 511-keV radiation from the Galactic Center region.

  7. Towards red-edge positions less sensitive to canopy biophysical parameters for leaf chlorophyll estimation using properties optique spectrales des feuilles (PROSPECT) and scattering by arbitrarily inclined leaves (SAILH) simulated data

    NARCIS (Netherlands)

    Cho, M.A.; Skidmore, A.K.; Atzberger, C.

    2008-01-01

    Several methods for extracting the chlorophyll sensitive red-edge position (REP) from hyperspectral data are reported in literature. This study is a continuation of a recent paper published as 'A new technique for extracting the red edge position from hyperspectral data: the linear extrapolation

  8. Belle II silicon vertex detector

    Energy Technology Data Exchange (ETDEWEB)

    Adamczyk, K. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Aihara, H. [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Angelini, C. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Aziz, T.; Babu, V. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bacher, S. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Bahinipati, S. [Indian Institute of Technology Bhubaneswar, Satya Nagar (India); Barberio, E.; Baroncelli, Ti.; Baroncelli, To. [School of Physics, University of Melbourne, Melbourne, Victoria 3010 (Australia); Basith, A.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Batignani, G. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bauer, A. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Behera, P.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Bergauer, T. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Bettarini, S. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bhuyan, B. [Indian Institute of Technology Guwahati, Assam 781039 (India); Bilka, T. [Faculty of Mathematics and Physics, Charles University, 121 16 Prague (Czech Republic); Bosi, F. [INFN Sezione di Pisa, I-56127 Pisa (Italy); Bosisio, L. [Dipartimento di Fisica, Università di Trieste, I-34127 Trieste (Italy); INFN Sezione di Trieste, I-34127 Trieste (Italy); and others

    2016-09-21

    The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector.

  9. Buried oxide layer in silicon

    Science.gov (United States)

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2001-01-01

    A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

  10. Silicon-micromachined microchannel plates

    International Nuclear Information System (INIS)

    Beetz, Charles P.; Boerstler, Robert; Steinbeck, John; Lemieux, Bryan; Winn, David R.

    2000-01-01

    Microchannel plates (MCP) fabricated from standard silicon wafer substrates using a novel silicon micromachining process, together with standard silicon photolithographic process steps, are described. The resulting SiMCP microchannels have dimensions of ∼0.5 to ∼25 μm, with aspect ratios up to 300, and have the dimensional precision and absence of interstitial defects characteristic of photolithographic processing, compatible with positional matching to silicon electronics readouts. The open channel areal fraction and detection efficiency may exceed 90% on plates up to 300 mm in diameter. The resulting silicon substrates can be converted entirely to amorphous quartz (qMCP). The strip resistance and secondary emission are developed by controlled depositions of thin films, at temperatures up to 1200 deg. C, also compatible with high-temperature brazing, and can be essentially hydrogen, water and radionuclide-free. Novel secondary emitters and cesiated photocathodes can be high-temperature deposited or nucleated in the channels or the first strike surface. Results on resistivity, secondary emission and gain are presented

  11. In the Blink of an Eye: Relating Positive-Feedback Sensitivity to Striatal Dopamine D2-Like Receptors through Blink Rate

    Science.gov (United States)

    Groman, Stephanie M.; James, Alex S.; Seu, Emanuele; Tran, Steven; Clark, Taylor A.; Harpster, Sandra N.; Crawford, Maverick; Burtner, Joanna Lee; Feiler, Karen; Roth, Robert H.; Elsworth, John D.; London, Edythe D.

    2014-01-01

    For >30 years, positron emission tomography (PET) has proven to be a powerful approach for measuring aspects of dopaminergic transmission in the living human brain; this technique has revealed important relationships between dopamine D2-like receptors and dimensions of normal behavior, such as human impulsivity, and psychopathology, particularly behavioral addictions. Nevertheless, PET is an indirect estimate that lacks cellular and functional resolution and, in some cases, is not entirely pharmacologically specific. To identify the relationships between PET estimates of D2-like receptor availability and direct in vitro measures of receptor number, affinity, and function, we conducted neuroimaging and behavioral and molecular pharmacological assessments in a group of adult male vervet monkeys. Data gathered from these studies indicate that variation in D2-like receptor PET measurements is related to reversal-learning performance and sensitivity to positive feedback and is associated with in vitro estimates of the density of functional dopamine D2-like receptors. Furthermore, we report that a simple behavioral measure, eyeblink rate, reveals novel and crucial links between neuroimaging assessments and in vitro measures of dopamine D2 receptors. PMID:25339755

  12. Photoionization dynamics of glycine adsorbed on a silicon cluster: ''On-the-fly'' simulations

    International Nuclear Information System (INIS)

    Shemesh, Dorit; Baer, Roi; Seideman, Tamar; Gerber, R. Benny

    2005-01-01

    Dynamics of glycine chemisorbed on the surface of a silicon cluster is studied for a process that involves single-photon ionization, followed by recombination with the electron after a selected time delay. The process is studied by ''on-the-fly'' molecular dynamics simulations, using the semiempirical parametric method number 3 (PM3) potential energy surface. The system is taken to be in the ground state prior to photoionization, and time delays from 5 to 50 fs before the recombination are considered. The time evolution is computed over 10 ps. The main findings are (1) the positive charge after ionization is initially mostly distributed on the silicon cluster. (2) After ionization the major structural changes are on the silicon cluster. These include Si-Si bond breaking and formation and hydrogen transfer between different silicon atoms. (3) The transient ionization event gives rise to dynamical behavior that depends sensitively on the ion state lifetime. Subsequent to 45 fs evolution in the charged state, the glycine molecule starts to rotate on the silicon cluster. Implications of the results to various processes that are induced by transient transition to a charged state are discussed. These include inelastic tunneling in molecular devices, photochemistry on conducting surfaces, and electron-molecule scattering

  13. Highly sensitive silicon microreactor for catalyst testing

    DEFF Research Database (Denmark)

    Henriksen, Toke Riishøj; Olsen, Jakob Lind; Vesborg, Peter Christian Kjærgaard

    2009-01-01

    by directing the entire gas flow through the catalyst bed to a mass spectrometer, thus ensuring that nearly all reaction products are present in the analyzed gas flow. Although the device can be employed for testing a wide range of catalysts, the primary aim of the design is to allow characterization of model...... catalysts which can only be obtained in small quantities. Such measurements are of significant fundamental interest but are challenging because of the low surface areas involved. The relationship between the reaction zone gas flow and the pressure in the reaction zone is investigated experimentally......, it is found that platinum catalysts with areas as small as 15 mu m(2) are conveniently characterized with the device. (C) 2009 American Institute of Physics. [doi:10.1063/1.3270191]...

  14. Breakup of loosely bound nuclei at intermediate energies for nuclear astrophysics and the development of a position sensitive microstrip detector system and its readout electronics using ASICs technologies

    Energy Technology Data Exchange (ETDEWEB)

    Bertulani, Carlos A. [Texas A & M Univ., Commerce, TX (United States)

    2016-01-12

    The work performed under this grant has led to the development of a detection system that will be used to measure reaction rates for proton or neutron capture reactions at stellar energies on radioactive ions far from stability. The reaction rates are needed to better understand the physics of nucleosynthesis in explosive stellar processes such as supernovae and x-ray burst events. The radioactive ions will be produced at the Radioactive Ion Beam Facility (RIBF) at RIKEN near Tokyo, Japan. During the course of this work, the group involved in this project has expanded by several institutions in Europe and Japan and now involves collaborators from the U.S., Japan, Hungary, Romania, Germany, Spain, Italy, China, and South Korea. As part of the project, a novel design based on large-area silicon detectors has been built and tested. The work has involved mechanical construction of a special purpose vacuum chamber, with a precision mounting system for the silicon detectors, development of a new ASICs readout system that has applications with a wide variety of silicon detector systems, and the development of a data acquisition system that is integrated into the computer system being used at RIBF. The parts noted above that are needed to carry out the research program are completed and ready for installation. Several approved experiments that will use this system will be carried out in the near future. The experimental work has been delayed due to a large increase in the cost and availability of electrical power for RIBF that occurred following the massive earthquake and tsunami that hit Japan in the spring of 2011. Another component of the research carried out with this grant involved developing the theoretical tools that are required to extract the information from the experiments that is needed to determine the stellar reaction rates. The tools developed through this part of the work will be made freely available for general use.

  15. Sensitive monitoring of monoterpene metabolites in human urine using two-step derivatisation and positive chemical ionisation-tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Lukas [Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, University of Erlangen-Nuremberg, Schillerstrasse 25/29, 91054 Erlangen (Germany); Belov, Vladimir N. [Max Planck Institute for Biophysical Chemistry, Facility for Synthetic Chemistry, Am Fassberg 11, 37077 Göttingen (Germany); Göen, Thomas, E-mail: Thomas.Goeen@ipasum.med.uni-erlangen.de [Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, University of Erlangen-Nuremberg, Schillerstrasse 25/29, 91054 Erlangen (Germany)

    2013-09-02

    Highlights: •Sensitive monitoring of 10 metabolites of (R)-limonene, α-pinene, and Δ{sup 3}-carene in human urine samples. •Fast and simple sample preparation and derivatisation procedure using two-step silylation for unreactive tertiary hydroxyl groups. •Synthesis of reference substances and isotopically labelled internal standards of (R)-limonene, α-pinene, and Δ{sup 3}-carene metabolites. •Study on (R)-limonene, α-pinene, and Δ{sup 3}-carene metabolite background exposure of 36 occupationally unexposed volunteers. -- Abstract: A gas chromatographic–positive chemical ionisation-tandem mass spectrometric (GC–PCI-MS/MS) method for the simultaneous determination of 10 oxidative metabolites of the monoterpenoid hydrocarbons α-pinene, (R)-limonene, and Δ{sup 3}-carene ((+)-3-carene) in human urine was developed and tested for the monoterpene biomonitoring of the general population (n = 36). The method involves enzymatic cleavage of the glucuronides followed by solid-supported liquid–liquid extraction and derivatisation using a two-step reaction with N,O-bis(trimethylsilyl)-trifluoroacetamide and N-(trimethylsilyl)imidazole. The method proved to be both sensitive and reliable with detection limits ranging from 0.1 to 0.3 μg L{sup −1}. In contrast to the frequent and distinct quantities of (1S,2S,4R)-limonene-1,2-diol, the (1R,2R,4R)-stereoisomer could not be detected. The expected metabolite of (+)-3-carene, 3-caren-10-ol was not detected in any of the samples. All other metabolites were detected in almost all urine samples. The procedure enables for the first time the analysis of trace levels of a broad spectrum of mono- and bicyclic monoterpenoid metabolites (alcohols, diols, and carboxylic acids) in human urine. This analytical procedure is a powerful tool for population studies as well as for the discovery of human metabolism and toxicokinetics of monoterpenes.

  16. Comparative silicone breast implant evaluation using mammography, sonography, and magnetic resonance imaging: experience with 59 implants.

    Science.gov (United States)

    Ahn, C Y; DeBruhl, N D; Gorczyca, D P; Shaw, W W; Bassett, L W

    1994-10-01

    With the current controversy regarding the safety of silicone implants, the detection and evaluation of implant rupture are causing concern for both plastic surgeons and patients. Our study obtained comparative value analysis of mammography, sonography, and magnetic resonance imaging (MRI) in the detection of silicone implant rupture. Twenty-nine symptomatic patients (total of 59 silicone implants) were entered into the study. Intraoperative findings revealed 21 ruptured implants (36 percent). During physical examination, a positive "squeeze test" was highly suggestive of implant rupture. Mammograms were obtained of 51 implants (sensitivity 11 percent, specificity 89 percent). Sonography was performed on 57 implants (sensitivity 70 percent, specificity 92 percent). MRI was performed on 55 implants (sensitivity 81 percent, specificity 92 percent). Sonographically, implant rupture is demonstrated by the "stepladder sign." Double-lumen implants may appear as false-positive results for rupture on sonography. On MRI, the "linguine sign" represents disrupted fragments of a ruptured implant. The most reliable imaging modality for implant rupture detection is MRI, followed by sonogram. Mammogram is the least reliable. Our study supports the clinical indication and diagnostic value of sonogram and MRI in the evaluation of symptomatic breast implant patients.

  17. 3D characterisation of tool wear whilst diamond turning silicon

    OpenAIRE

    Durazo-Cardenas, Isidro Sergio; Shore, Paul; Luo, X.; Jacklin, T.; Impey, S. A.; Cox, A.

    2006-01-01

    Nanometrically smooth infrared silicon optics can be manufactured by the diamond turning process. Due to its relatively low density, silicon is an ideal optical material for weight sensitive infrared (IR) applications. However, rapid diamond tool edge degradation and the effect on the achieved surface have prevented significant exploitation. With the aim of developing a process model to optimise the diamond turning of silicon optics, a series of experimental trials were devi...

  18. Silicon radiation detector analysis using back electron beam induced current

    International Nuclear Information System (INIS)

    Guye, R.

    1987-01-01

    A new technique for the observation and analysis of defects in silicon radiation detectors is described. This method uses an electron beam from a scanning electron microscope (SEM) impinging on the rear side of the p + n junction of the silicon detector, which itself is active and detects the electron beam induced current (EBIC). It is shown that this current is a sensitive probe of localized trapping centers, either at the junction surface or somewhere in the volume of the silicon crystal. (orig.)

  19. Fine Tuning of CaV1.3 Ca2+ channel properties in adult inner hair cells positioned in the most sensitive region of the Gerbil Cochlea.

    Directory of Open Access Journals (Sweden)

    Valeria Zampini

    Full Text Available Hearing relies on faithful signal transmission by cochlear inner hair cells (IHCs onto auditory fibres over a wide frequency and intensity range. Exocytosis at IHC ribbon synapses is triggered by Ca(2+ inflow through Ca(V1.3 (L-type Ca(2+ channels. We investigated the macroscopic (whole-cell and elementary (cell-attached properties of Ca(2+ currents in IHCs positioned at the middle turn (frequency ∼ 2 kHz of the adult gerbil cochlea, which is their most sensitive hearing region. Using near physiological recordings conditions (body temperature and a Na(+ based extracellular solution, we found that the macroscopic Ca(2+ current activates and deactivates very rapidly (time constant below 1 ms and inactivates slowly and only partially. Single-channel recordings showed an elementary conductance of 15 pS, a sub-ms latency to first opening, and a very low steady-state open probability (Po: 0.024 in response to 500-ms depolarizing steps at ∼-18 mV. The value of Po was significantly larger (0.06 in the first 40 ms of membrane depolarization, which corresponds to the time when most Ca(2+ channel openings occurred clustered in bursts (mean burst duration: 19 ms. Both the Po and the mean burst duration were smaller than those previously reported in high-frequency basal IHCs. Finally, we found that middle turn IHCs are likely to express about 4 times more Ca(2+ channels per ribbon than basal cells. We propose that middle-turn IHCs finely-tune Ca(V1.3 Ca(2+ channel gating in order to provide reliable information upon timing and intensity of lower-frequency sounds.

  20. Fine Tuning of CaV1.3 Ca2+ channel properties in adult inner hair cells positioned in the most sensitive region of the Gerbil Cochlea.

    Science.gov (United States)

    Zampini, Valeria; Johnson, Stuart L; Franz, Christoph; Knipper, Marlies; Holley, Matthew C; Magistretti, Jacopo; Russo, Giancarlo; Marcotti, Walter; Masetto, Sergio

    2014-01-01

    Hearing relies on faithful signal transmission by cochlear inner hair cells (IHCs) onto auditory fibres over a wide frequency and intensity range. Exocytosis at IHC ribbon synapses is triggered by Ca(2+) inflow through Ca(V)1.3 (L-type) Ca(2+) channels. We investigated the macroscopic (whole-cell) and elementary (cell-attached) properties of Ca(2+) currents in IHCs positioned at the middle turn (frequency ∼ 2 kHz) of the adult gerbil cochlea, which is their most sensitive hearing region. Using near physiological recordings conditions (body temperature and a Na(+) based extracellular solution), we found that the macroscopic Ca(2+) current activates and deactivates very rapidly (time constant below 1 ms) and inactivates slowly and only partially. Single-channel recordings showed an elementary conductance of 15 pS, a sub-ms latency to first opening, and a very low steady-state open probability (Po: 0.024 in response to 500-ms depolarizing steps at ∼-18 mV). The value of Po was significantly larger (0.06) in the first 40 ms of membrane depolarization, which corresponds to the time when most Ca(2+) channel openings occurred clustered in bursts (mean burst duration: 19 ms). Both the Po and the mean burst duration were smaller than those previously reported in high-frequency basal IHCs. Finally, we found that middle turn IHCs are likely to express about 4 times more Ca(2+) channels per ribbon than basal cells. We propose that middle-turn IHCs finely-tune Ca(V)1.3 Ca(2+) channel gating in order to provide reliable information upon timing and intensity of lower-frequency sounds.