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Sample records for channel electron multiplier

  1. Channel electron multipliers

    International Nuclear Information System (INIS)

    Seidman, A.; Avrahami, Z.; Sheinfux, B.; Grinberg, J.

    1976-01-01

    A channel electron multiplier is described having a tubular wall coated with a secondary-electron emitting material and including an electric field for accelerating the electrons, the electric field comprising a plurality of low-resistive conductive rings each alternating with a high-resistive insulating ring. The thickness of the low-resistive rings is many times larger than that of the high-resistive rings, being in the order of tens of microns for the low-resistive rings and at least one order of magnitude lower for the high-resistive rings; and the diameter of the channel tubular walls is also many times larger than the thickness of the high-resistive rings. Both single-channel and multiple-channel electron multipliers are described. A very important advantage, particularly in making multiple-channel multipliers, is the simplicity of the procedure that may be used in constructing such multipliers. Other operational advantages are described

  2. Spin sensitivity of a channel electron multiplier

    International Nuclear Information System (INIS)

    Scholten, R.E.; McClelland, J.J.; Kelley, M.H.; Celotta, R.J.

    1988-01-01

    We report direct measurements of the sensitivity of a channel electron multiplier to electrons with different spin orientations. Four regions of the multiplier cone were examined using polarized electrons at 100-eV incident energy. Pulse counting and analog modes of operation were both investigated and in each case the observed spin effects were less than 0.5%

  3. Exponential decay and exponential recovery of modal gains in high count rate channel electron multipliers

    International Nuclear Information System (INIS)

    Hahn, S.F.; Burch, J.L.

    1980-01-01

    A series of data on high count rate channel electron multipliers revealed an initial drop and subsequent recovery of gains in exponential fashion. The FWHM of the pulse height distribution at the initial stage of testing can be used as a good criterion for the selection of operating bias voltage of the channel electron multiplier

  4. Effect of the channel electron multiplier connection diagram on its parameters

    International Nuclear Information System (INIS)

    Ajnbund, M.R.

    1976-01-01

    Basic alternatives of connection of a channel electron multiplier are described. A dependence of a gain factor and amplitude resolution of the channel electron multiplier upon its connection diagram is studied. The studies have shown that the maximum gain factor is typical of an open-output circuit where the signal is recorded from the anode of the channel electron multiplier at a potential with respect to the channel outlet. The highest amplitude resolution is inherent in a separate-anode circuit where the loading resistance is connected directly to the channel outlet

  5. Ceramic Electron Multiplier

    International Nuclear Information System (INIS)

    Comby, G.

    1996-01-01

    The Ceramic Electron Multipliers (CEM) is a compact, robust, linear and fast multi-channel electron multiplier. The Multi Layer Ceramic Technique (MLCT) allows to build metallic dynodes inside a compact ceramic block. The activation of the metallic dynodes enhances their secondary electron emission (SEE). The CEM can be used in multi-channel photomultipliers, multi-channel light intensifiers, ion detection, spectroscopy, analysis of time of flight events, particle detection or Cherenkov imaging detectors. (auth)

  6. Utilization of a channel electron multiplier for counting-measurement on condensed molecular jet

    International Nuclear Information System (INIS)

    Le Bihan, A.M.; Bottiglioni, F.; Coutant, J.; Fois, M.; CEA Centre d'Etudes Nucleaires de Fontenay-aux-Roses, 92

    1974-01-01

    A channel electron multiplier has been used for counting ionized clusters containing up to a few thousands molecules; clusters are accelerated towards a negative (approximately-220V) copper target; a larger negative bias (approximately-3000V) is applied to the multiplier entrance so as to collect positive secondary ions and/or reflected cluster fragments; in the present application this gives better signal to noise ratio than detecting clusters directly or by secondary electron emission on the target [fr

  7. A zerotime detector for nuclear fragments using channel electron multiplier plates

    International Nuclear Information System (INIS)

    Sundqvist, B.

    1975-01-01

    The literature on zerotime detectors which use the emission of secondary electrons from a thin foil is reviewed. The construction of a zerotime detector using multiplication of the secondary electrons with two Mullard channel electron multiplier plates (CEMP) in tandem is described. Results of tests of such a detector with α particles from a natural α source are given. Total time resolutions of about 200 ps (FWHM) with a Si(Sb) detector as the stop detector has been achieved. The contribution from the zerotime detector is estimated to be less than 150 ps (FWHM). The application of this detector technique to the construction of a heavy-ion spectrometer and a 8 Be detector is described. (Auth)

  8. Microchannel electron multiplier

    International Nuclear Information System (INIS)

    Beranek, I.; Janousek, L.; Vitovsky, O.

    1981-01-01

    A microchannel electron multiplier is described for detecting low levels of alpha, beta, soft X-ray and UV radiations. It consists of a glass tube or a system of tubes of various shapes made of common technological glass. The inner tube surface is provided with an active coat with photoemitter and secondary emitter properties. (B.S.)

  9. Photoionisation detection of single 87Rb-atoms using channel electron multipliers

    International Nuclear Information System (INIS)

    Henkel, Florian Alexander

    2011-01-01

    Fast and efficient detection of single atoms is a universal requirement concerning modern experiments in atom physics, quantum optics, and precision spectroscopy. In particular for future quantum information and quantum communication technologies, the efficient readout of qubit states encoded in single atoms or ions is an elementary prerequisite. The rapid development in the field of quantum optics and atom optics in the recent years has enabled to prepare individual atoms as quantum memories or arrays of single atoms as qubit registers. With such systems, the implementation of quantum computation or quantum communication protocols seems feasible. This thesis describes a novel detection scheme which enables fast and efficient state analysis of single neutral atoms. The detection scheme is based on photoionisation and consists of two parts: the hyperfine-state selective photoionisation of single atoms and the registration of the generated photoion-electron pairs via two channel electron multipliers (CEMs). In this work, both parts were investigated in two separate experiments. For the first step, a photoionisation probability of p ion =0.991 within an ionisation time of t ion =386 ns is achieved for a single 87 Rb-atom in an optical dipole trap. For the second part, a compact detection system for the ionisation fragments was developed consisting of two opposing CEM detectors. Measurements show that single neutral atoms can be detected via their ionisation fragments with a detection efficiency of η atom =0.991 within a detection time of t det =415.5 ns. In a future combined setup, this will allow the state-selective readout of optically trapped, single neutral 87 Rb-atoms via photoionisation detection with an estimated detection efficiency η=0.982 and a detection time of t tot = 802 ns. Although initially developed for single 87 Rb-atoms, the concept of photoionisation detection is in principle generally applicable to any atomic or molecular species. As efficient

  10. Photoionisation detection of single {sup 87}Rb-atoms using channel electron multipliers

    Energy Technology Data Exchange (ETDEWEB)

    Henkel, Florian Alexander

    2011-09-02

    Fast and efficient detection of single atoms is a universal requirement concerning modern experiments in atom physics, quantum optics, and precision spectroscopy. In particular for future quantum information and quantum communication technologies, the efficient readout of qubit states encoded in single atoms or ions is an elementary prerequisite. The rapid development in the field of quantum optics and atom optics in the recent years has enabled to prepare individual atoms as quantum memories or arrays of single atoms as qubit registers. With such systems, the implementation of quantum computation or quantum communication protocols seems feasible. This thesis describes a novel detection scheme which enables fast and efficient state analysis of single neutral atoms. The detection scheme is based on photoionisation and consists of two parts: the hyperfine-state selective photoionisation of single atoms and the registration of the generated photoion-electron pairs via two channel electron multipliers (CEMs). In this work, both parts were investigated in two separate experiments. For the first step, a photoionisation probability of p{sub ion}=0.991 within an ionisation time of t{sub ion}=386 ns is achieved for a single {sup 87}Rb-atom in an optical dipole trap. For the second part, a compact detection system for the ionisation fragments was developed consisting of two opposing CEM detectors. Measurements show that single neutral atoms can be detected via their ionisation fragments with a detection efficiency of {eta}{sub atom}=0.991 within a detection time of t{sub det}=415.5 ns. In a future combined setup, this will allow the state-selective readout of optically trapped, single neutral {sup 87}Rb-atoms via photoionisation detection with an estimated detection efficiency {eta}=0.982 and a detection time of t{sub tot} = 802 ns. Although initially developed for single {sup 87}Rb-atoms, the concept of photoionisation detection is in principle generally applicable to any

  11. The detection of hard x-rays (10-140 KeV) by channel plate electron multipliers

    International Nuclear Information System (INIS)

    Bateman, J.E.

    1976-12-01

    Results are presented indicating that hard X-rays in the energy range 10 to 50 keV can be detected with good efficiency (5 to 10%) in channel plate electron multipliers (CPEM). From 50 keV to 140 keV the detection efficiency lies in the range 1 to 2%. A simple physical model is developed which indicates that not only can good detection efficiency be obtained but that very good X-ray imaging is possible. The model predicts that with further development, a wideband, hard X-ray detector can be realised with a detection efficiency in the range 5 to 20% and spatial response better than 10 lp/mm in the energy range 10 to 140 keV. (author)

  12. Detector system for particle or quantum radiation with a multitude of channel secondary electron multipliers arranged in the form of a laminar matrix

    Energy Technology Data Exchange (ETDEWEB)

    Manley, B W; Burgess, H

    1979-01-11

    The detector system may be used in diagnostic X-ray or gamma radiography. It essentially consists of a great number of channel secondary electron multipliers assigned to which are two electrodes consisting of parallel electrode strips each. The strips in one electrode are some distance away from those of the other electrode and are shifted by 90/sup 0/ with respect to them. Each electrode strip has got a connection joined to a charge detection circuit. This charge detection circuit contains a logic circuit by which a reliable assessment of the surface distribution of the particles resp. quanta hitting the channel secondary electron multipliers is made possible.

  13. Channel electron multiplier operated on a sounding rocket without a cryogenic vacuum pump from 120 to 80 km altitude

    Science.gov (United States)

    Dickson, Shannon; Gausa, Michael; Robertson, Scott; Sternovsky, Zoltan

    2013-04-01

    We demonstrate that a channel electron multiplier (CEM) can be operated on a sounding rocket in the pulse-counting mode from 120 km to 80 km altitude without the cryogenic evacuation used in the past. Evacuation of the CEM is provided only by aerodynamic flow around the rocket. This demonstration is motivated by the need for additional flights of mass spectrometers to clarify the fate of metallic compounds and ions ablated from micrometeorites and their possible role in the nucleation of noctilucent clouds. The CEMs were flown as guest instruments on two sounding rockets to the mesosphere. Modeling of the aerodynamic flow around the payload with Direct Simulation Monte-Carlo (DSMC) code showed that the pressure is reduced below ambient in the void behind (relative to the direction of motion) an aft-facing surface. An enclosure containing the CEM was placed forward of an aft-facing deck and a valve was opened during flight to expose the CEM to the aerodynamically evacuated region behind it. The CEM operated successfully from apogee down to ∼80 km. A Pirani gauge confirmed pressures reduced to as low as 20% of ambient with the extent of reduction dependent upon altitude and velocity. Additional DSMC simulations indicate that there are alternate payload designs with improved aerodynamic pumping for forward mounted instruments such as mass spectrometers.

  14. The gas electron multiplier (GEM)

    CERN Document Server

    Bouclier, Roger; Dominik, Wojciech; Hoch, M; Labbé, J C; Million, Gilbert; Ropelewski, Leszek; Sauli, Fabio; Sharma, A

    1996-01-01

    We describe operating priciples and results obtained with a new detector component: the Gas Electrons Multiplier (GEM). Consisting of a thin composite sheet with two metal layers separated by a thin insulator, and pierced by a regular matrix of open channels, the GEM electrode, inserted on the path of electrons in a gas detector, allows to transfer the charge with an amplification factor approaching ten. Uniform response and high rate capability are demonstrated. Coupled to another device, multiwire or micro-strip chamber, the GEM electrode permit to obtain higher gains or less critical operation; separation of the sensitive (conversion) volume and the detection volume has other advantages, as a built-in delay (useful for triggering purposes) and the possibility of applying high fields on the photo-cathode of ring imaging detectors to improve efficiency. Multiple GEM grids in the same gas volume allow to obtain large amplification factors in a succession of steps, leading to the realization of an effective ga...

  15. Effects of tritium on electron multiplier performance

    International Nuclear Information System (INIS)

    Kerst, R.A.; Malinowski, M.E.

    1980-01-01

    In developing diagnostic instruments for fusion reactors, it is necessary to measure the effects of tritium contamination on channel electron multipliers (CEM). A CEM was exposed to T 2 pressures of up to 1.5 x 10 -1 Pa, with exposure quantities ranging up to 8800 Pa-s. The counting rate of the CEM is shown to consist of a prompt (Type I) signal caused by gas-phase tritium and a residual (Type II) signal, probably caused by near-surface tritium. The potential for using CEMs for observing the dynamics of tritium adsorption and absorption is discussed

  16. GEM the gas electron multiplier

    CERN Document Server

    Sauli, Fabio

    1997-01-01

    We describe the basic structure and operation of a new device, the Gas Electron Multiplier. Consisting in a polymer foil, metal-clad on both sides and perforated by a high density of holes, the GEM mesh allows to pre-amplify charges released in the gas with good uniformity and energy. Coupled to a micro-strip plate, the pre-amplification element allows to preserve high rate capability and resolution at considerably lower operating voltages, thus completely eliminating discharges and instabilities. Several GEM grids can be operated in cascade; charge gains are large enough to allow detection of signals in the ionization mode on the last element, permitting the use of a simple printed circuit as read-out electrode. Two-dimensional read-out can then be easily implemented. A new generation of simple, reliable and cheap fast position sensitive detectors seems at hand.

  17. Tritium-caused background currents in electron multipliers

    International Nuclear Information System (INIS)

    Malinowski, M.E.

    1979-05-01

    One channel electron multiplier (Galileo No. 4501) and one 14 stage Be/Cu multiplier (Dumont No. SPM3) were exposed to tritium pressures between approx. 10 -7 Torr to 10 -3 Torr in amounts from approx. 10 -5 Torr-s to 60 Torr-s and the β-decay caused currents in the multipliers measured. The background currents in both multipliers consisted of two components: (1) a high, reversible current which was proportional to the tritium exposure pressure; and (2) a lower, irreversible background current which increased with increasing cumulative tritium exposure. The β-decay caused currents in each multiplier increased the same way with exposure, suggesting the detected electrons arose from decaying tritium adsorbed on surfaced external to the multipliers

  18. Gaseous Electron Multiplier (GEM) Detectors

    Science.gov (United States)

    Gnanvo, Kondo

    2017-09-01

    Gaseous detectors have played a pivotal role as tracking devices in the field of particle physics experiments for the last fifty years. Recent advances in photolithography and micro processing techniques have enabled the transition from Multi Wire Proportional Chambers (MWPCs) and Drift Chambers to a new family of gaseous detectors refer to as Micro Pattern Gaseous Detectors (MPGDs). MPGDs combine the basic gas amplification principle with micro-structure printed circuits to provide detectors with excellent spatial and time resolution, high rate capability, low material budget and high radiation tolerance. Gas Electron Multiplier (GEMs) is a well-established MPGD technology invented by F. Sauli at CERN in 1997 and deployed various high energy physics (HEP) and nuclear NP experiment for tracking systems of current and future NP experiments. GEM detector combines an exceptional high rate capability (1 MHz / mm2) and robustness against harsh radiation environment with excellent position and timing resolution performances. Recent breakthroughs over the past decade have allowed the possibility for large area GEMs, making them cost effective and high-performance detector candidates to play pivotal role in current and future particle physics experiments. After a brief introduction of the basic principle of GEM technology, I will give a brief overview of the GEM detectors used in particle physics experiments over the past decades and especially in the NP community at Thomas Jefferson National Laboratory (JLab) and Brookhaven National Laboratory (BNL). I will follow by a review of state of the art of the new GEM development for the next generation of colliders such as Electron Ion Collider (EIC) or High Luminosity LHC and future Nuclear Physics experiments. I will conclude with a presentation of the CERN-based RD51 collaboration established in 2008 and its major achievements regarding technological developments and applications of MPGDs.

  19. COINCIDENCES BETWEEN ELECTRONS AND TARGET IONS TO IDENTIFY CAPTURE CHANNELS IN COLLISIONS OF MULTIPLY CHARGED IONS ON GAS TARGETS

    NARCIS (Netherlands)

    POSTHUMUS, JH; MORGENSTERN, R

    1992-01-01

    We have investigated multielectron capture processes in collisions of Ar9+ on Ar by measuring the resulting Auger electrons in coincidence with charge-state-analyzed target ions. In this way it was possible to reconstruct partial electron energy spectra, each corresponding to a particular number of

  20. Electron cyclotron resonance multiply charged ion sources

    International Nuclear Information System (INIS)

    Geller, R.

    1975-01-01

    Three ion sources, that deliver multiply charged ion beams are described. All of them are E.C.R. ion sources and are characterized by the fact that the electrons are emitted by the plasma itself and are accelerated to the adequate energy through electron cyclotron resonance (E.C.R.). They can work without interruption during several months in a quasi-continuous regime. (Duty cycle: [fr

  1. Evaporator line for special electron tubes, in particular electron multipliers

    International Nuclear Information System (INIS)

    Richter, M.

    1984-01-01

    The invention has been aimed at reducing the effort for preventing short circuits in achieving certain material-dependent effects e.g. secondary emission, by deposition through evaporation in the production of electron tubes, in particular electron multipliers

  2. Electronic de-multipliers; Demultiplicateurs electroniques

    Energy Technology Data Exchange (ETDEWEB)

    Ailloud, J

    1948-07-01

    The counting of a huge number of events, randomly or periodically distributed, requires the use of electronic counters which can work with a flow of up to 500000 events per second, while mechanical systems have a much lower resolution which leads to an important percentage of losses (non-counted events). Thus, hybrid systems are generally used which comprise an electronic part with fast counting capabilities but low recording capacities, and a mechanical part for the recording of the successive resets of the electronic part. This report describes the basic elementary circuits of these electronic counters (de-multipliers): dividers by 2 and 5 and flip-flop circuits using triode and pentode valves for the counting of events in the decimal system. (J.S.)

  3. Single electron based binary multipliers with overflow detection ...

    African Journals Online (AJOL)

    electron based device. Multipliers with overflow detection based on serial and parallel prefix computation algorithm are elaborately discussed analytically and designed. The overflow detection circuits works in parallel with a simplified multiplier to ...

  4. Charge amplification and transfer processes in the gas electron multiplier

    International Nuclear Information System (INIS)

    Bachmann, S.; Bressan, A.; Ropelewski, L.; Sauli, F.; Sharma, A.; Moermann, D.

    1999-01-01

    We report the results of systematic investigations on the operating properties of detectors based on the gas electron multiplier (GEM). The dependence of gain and charge collection efficiency on the external fields has been studied in a range of values for the hole diameter and pitch. The collection efficiency of ionization electrons into the multiplier, after an initial increase, reaches a plateau extending to higher values of drift field the larger the GEM voltage and its optical transparency. The effective gain, fraction of electrons collected by an electrode following the multiplier, increases almost linearly with the collection field, until entering a steeper parallel plate multiplication regime. The maximum effective gain attainable increases with the reduction in the hole diameter, stabilizing to a constant value at a diameter approximately corresponding to the foil thickness. Charge transfer properties appear to depend only on ratios of fields outside and within the channels, with no interaction between the external fields. With proper design, GEM detectors can be optimized to satisfy a wide range of experimental requirements: tracking of minimum ionizing particles, good electron collection with small distortions in high magnetic fields, improved multi-track resolution and strong ion feedback suppression in large volume and time-projection chambers

  5. Performance of gas electron multiplier (GEM) detector

    International Nuclear Information System (INIS)

    Han, S. H.; Moon, B. S.; Kim, Y. K.; Chung, C. E.; Kang, H. D.; Cho, H. S.

    2002-01-01

    We have investigated in detail the operating properties of Gas Electron Multiplier (GEM) detectors with a double conical and a cylindrical structure in a wide range of external fields and GEM voltages. With the double conical GEM, the gain gradually increased with time by 10%; whereas this surface charging was eliminated with the cylindrical GEM. Effective gains above 1000 were easily observed over a wide range of collection field strengths in a gas mixture of Ar/CO 2 (70/30). The transparency and electron collection efficiency were found to depend on the ratio of external field and the applied GEM voltage; the mutual influence of both drift and collection fields was found to be trivial

  6. Charge transfer in gas electron multipliers

    Energy Technology Data Exchange (ETDEWEB)

    Ottnad, Jonathan; Ball, Markus; Ketzer, Bernhard; Ratza, Viktor; Razzaghi, Cina [HISKP, Bonn University, Nussallee 14-16, D-53115 Bonn (Germany)

    2015-07-01

    In order to efficiently employ a Time Projection Chamber (TPC) at interaction rates higher than ∝1 kHz, as foreseen e.g. in the ALICE experiment (CERN) and at CB-ELSA (Bonn), a continuous operation and readout mode is required. A necessary prerequisite is to minimize the space charge coming from the amplification system and to maintain an excellent spatial and energy resolution. Unfortunately these two goals can be in conflict to each other. Gas Electron Multipliers (GEM) are one candidate to fulfill these requirements. It is necessary to understand the processes within the amplification structure to find optimal operation conditions. To do so, we measure the charge transfer processes in and between GEM foils with different geometries and field configurations, and use an analytical model to describe the results. This model can then be used to predict and optimize the performance. The talk gives the present status of the measurements and describes the model.

  7. Fabrication and measurement of gas electron multiplier

    International Nuclear Information System (INIS)

    Zhang Minglong; Xia Yiben; Wang Linjun; Gu Beibei; Wang Lin; Yang Ying

    2005-01-01

    Gas electron multiplier (GEM) with special performance has been widely used in the field of radiation detectors. In this work, GEM film was fabricated using a 50 μm -thick kapton film by the therma evaporation and laser masking drilling technique. GEM film has many uniformly arrayed holes with a diameter of 100 μm and a gap of 223 μm. It was then set up to a gas-flowing detector with an effective area of 3 x 3 cm 2 , 5.9 keV X-ray generated from a 55 Fe source was used to measure the pulse height distribution of GEM operating at various high voltage and gas proportion. The effect of high potential and gas proportion on the count rate and the energy resolution was discussed in detail. The results indicate that GEM has a very high ratio of signal to noise and better energy resolution of 18.2%. (authors)

  8. Production processes of multiply charged ions by electron impact

    International Nuclear Information System (INIS)

    Oda, Nobuo

    1980-02-01

    First, are compared the foil or gas stripper and the ion sources utilizing electron-atom ionizing collisions, which are practically used or are under development to produce multiply charged ions. A review is made of the fundamental physical parameters such as successive ionization potentials and various ionization cross sections by electron impact, as well as the primary processes in multiply charged ion production. Multiply charged ion production processes are described for the different existing ion sources such as high temperature plasma type, ion-trapping type and discharge type. (author)

  9. Electronic de-multipliers II (ring-shape systems)

    International Nuclear Information System (INIS)

    Raievski, V.

    1948-09-01

    This report describes a new type of ring-shape fast electronic counter (de-multiplier) with a resolution capacity equivalent to the one made by Regener (Rev. of Scientific Instruments USA 1946, 17, 180-89) but requiring two-times less electronic valves. This report follows the general description of electronic de-multipliers made by J. Ailloud (CEA--001). The ring comprises 5 flip-flop circuits with two valves each. The different elements of the ring are calculated with enough details to allow the transfer of this calculation to different valve types. (J.S.)

  10. Timing characteristics of the VEhU-6 microchannel electron multipliers

    International Nuclear Information System (INIS)

    Bakhtizin, R.Z.; Yumaguzin, Yu.M.

    1982-01-01

    The VEhU-6 charnel electron multiplier timing characteristics are experimentally studied. Dependence of monoelectron pulse duration at the VEhU-6 output at different values of channel supply voltage is investigated. The VEhU-6 delay time is measured. Delay time increased from 10 to 30 ns with the increase of channel supply voltage from 2.8 to 3.2 kV (at approximately 10 5 pulse/s loading). Delay time increases with loading decrease

  11. The Tynode: A new vacuum electron multiplier

    Energy Technology Data Exchange (ETDEWEB)

    Graaf, Harry van der, E-mail: vdgraaf@nikhef.nl [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Akhtar, Hassan; Budko, Neil; Chan, Hong Wah; Hagen, Cornelis W. [Delft University of Technology, Delft (Netherlands); Hansson, Conny C.T. [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Nützel, Gert; Pinto, Serge D. [Photonis, Roden (Netherlands); Prodanović, Violeta; Raftari, Behrouz; Sarro, Pasqualina M. [Delft University of Technology, Delft (Netherlands); Sinsheimer, John; Smedley, John [Brookhaven National Laboratory, Upton, NY 11973 (United States); Tao, Shuxia [Eindhoven University of Technology/DIFFER (Netherlands); Theulings, Anne M.M.G. [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Vuik, Kees [Delft University of Technology, Delft (Netherlands)

    2017-03-01

    By placing, in vacuum, a stack of transmission dynodes (tynodes) on top of a CMOS pixel chip, a single free electron detector could be made with outstanding performance in terms of spatial and time resolution. The essential object is the tynode: an ultra thin membrane, which emits, at the impact of an energetic electron on one side, a multiple of electrons at the other side. The electron yields of tynodes have been calculated by means of GEANT-4 Monte Carlo simulations, applying special low-energy extensions. The results are in line with another simulation based on a continuous charge-diffusion model. By means of Micro Electro Mechanical System (MEMS) technology, tynodes and test samples have been realized. The secondary electron yield of several samples has been measured in three different setups. Finally, several possibilities to improve the yield are presented.

  12. Multiply excited molecules produced by photon and electron interactions

    International Nuclear Information System (INIS)

    Odagiri, T.; Kouchi, N.

    2006-01-01

    The photon and electron interactions with molecules resulting in the formation of multiply excited molecules and the subsequent decay are subjects of great interest because the independent electron model and Born-Oppenheimer approximation are much less reliable for the multiply excited states of molecules than for the ground and lower excited electronic states. We have three methods to observe and investigate multiply excited molecules: 1) Measurements of the cross sections for the emission of fluorescence emitted by neutral fragments in the photoexcitation of molecules as a function of incident photon energy [1-3], 2) Measurements of the electron energy-loss spectra tagged with the fluorescence photons emitted by neutral fragments [4], 3) Measurements of the cross sections for generating a pair of photons in absorption of a single photon by a molecule as a function of incident photon energy [5-7]. Multiply excited states degenerate with ionization continua, which make a large contribution in the cross section curve involving ionization processes. The key point of our methods is hence that we measure cross sections free from ionization. The feature of multiply excited states is noticeable in such a cross section curve. Recently we have measured: i) the cross sections for the emission of the Lyman- fluorescence in the photoexcitation of CH 4 as a function of incident photon energy in the range 18-51 eV, ii) the electron energy-loss spectrum of CH 4 tagged with the Lyman-photons at 80 eV incident electron energy and 10 electron scattering angle in the range of the energy loss 20-45 eV, in order to understand the formation and decay of the doubly excited methane in photon and electron interactions. [8] The results are summarized in this paper and the simultaneous excitation of two electrons by electron interaction is compared with that by photon interaction in terms of the oscillator strength. (authors)

  13. The Gas Electron Multiplier Chamber Exhibition LEPFest 2000

    CERN Multimedia

    2000-01-01

    The Gas Electron Multiplier (GEM) is a novel device introduced in 1996.Large area detectors based on this technology are in construction for high energy physics detectors.This technology can also be used for high-rate X-ray imaging in medical diagnostics and for monitoring irradiation during cancer treatment

  14. Statistics of electron multiplication in multiplier phototube: iterative method

    International Nuclear Information System (INIS)

    Grau Malonda, A.; Ortiz Sanchez, J.F.

    1985-01-01

    An iterative method is applied to study the variation of dynode response in the multiplier phototube. Three different situations are considered that correspond to the following ways of electronic incidence on the first dynode: incidence of exactly one electron, incidence of exactly r electrons and incidence of an average anti-r electrons. The responses are given for a number of steps between 1 and 5, and for values of the multiplication factor of 2.1, 2.5, 3 and 5. We study also the variance, the skewness and the excess of jurtosis for different multiplication factors. (author)

  15. Statistics of electron multiplication in a multiplier phototube; Iterative method

    International Nuclear Information System (INIS)

    Ortiz, J. F.; Grau, A.

    1985-01-01

    In the present paper an iterative method is applied to study the variation of dynode response in the multiplier phototube. Three different situation are considered that correspond to the following ways of electronic incidence on the first dynode: incidence of exactly one electron, incidence of exactly r electrons and incidence of an average r electrons. The responses are given for a number of steps between 1 and 5, and for values of the multiplication factor of 2.1, 2.5, 3 and 5. We study also the variance, the skewness and the excess of jurtosis for different multiplication factors. (Author) 11 refs

  16. On the fast response of charnel electron multipliers in coUnting mode operation

    International Nuclear Information System (INIS)

    Belyaevskij, O.A.; Gladyshev, I.L.; Korobochko, Yu.S.; Mineev, V.I.

    1983-01-01

    Dependences of amplitude distribution of pulses at the outlet of channel electron multipliers (CEM) and effectiveness of monitoring on counting rate at different supply voltages are determined. It is shown that the maximUm counting rate of CEM runs into 6x10 5 s -1 at short-term and 10 5 s -1 at long-term operation using monitoring eqUipment with operation threshold of 2.5 mV

  17. Charge-transfer properties in the gas electron multiplier

    International Nuclear Information System (INIS)

    Han, Sanghyo; Kim, Yongkyun; Cho, Hyosung

    2004-01-01

    The charge transfer properties of a gas electron multiplier (GEM) were systematically investigated over a broad range of electric field configurations. The electron collection efficiency and the charge sharing were found to depend on the external fields, as well as on the GEM voltage. The electron collection efficiency increased with the collection field up to 90%, but was essentially independent of the drift field strength. A double conical GEM has a 10% gain increase with time due to surface charging by avalanche ions whereas this effect was eliminated with the cylindrical GEM. The positive-ion feedback is also estimated. (author)

  18. Development of a thick gas electron multiplier for microdosimetry

    International Nuclear Information System (INIS)

    Orchard, G.M.; Chin, K.; Prestwich, W.V.; Waker, A.J.; Byun, S.H.

    2011-01-01

    A new tissue-equivalent proportional counter based on a thick gas electron multiplier (THGEM) was developed and tested for microdosimetry. A systematic test was conducted at the McMaster Accelerator Laboratory to investigate the overall performance of the prototype detector. A mixed neutron-gamma-ray radiation field was generated using the 7 Li(p,n) reaction. The detector was operated at low voltage initially to test the stability and then the relative multiplication gain was measured as a function of the operating high voltage. A drift potential of 100 V and a THGEM bias of 727 V generated a multiplication gain sufficient for the detection of both neutron and gamma-ray radiation. A consistent microdosimetric pattern was observed between the THGEM detector and standard TEPC for microdosimetry.

  19. Research on nonlinearity effect of secondary electron multiplier

    International Nuclear Information System (INIS)

    Wei Xingjian; Liao Junsheng; Deng Dachao; Yu Chunrong; Yuan Li

    2007-01-01

    The nonlinearity of secondary electron multiplier (SEM) of a thermal ionization mass spectrometer has been researched by using UTB-500 uranium isotope reference material and multi-collecting technique. The results show that the nonlinearity effect of SEM exists in the whole ion counting range, and there is an extreme point of the nonlinearity when the ion counting rate is about 20000 cps. The deviation between measured value of the extreme point and the reference value of the reference sample can be up to 3%, and the nonlinearity obeys logarithm linearity law on both sides of extreme point. A kind of mathematics model of nonlinearity calibration has been put forward. Using this model, the nonlinearity of SEM of TIMS can be calibrated. (authors)

  20. Investigation of the Decelerating Field of an Electron Multiplier under Negative Ion Impact

    DEFF Research Database (Denmark)

    Larsen, Elfinn; Kjeldgaard, K.

    1973-01-01

    The effect of the decelerating field of an electron multiplier towards negative ions was investigated under standard mass spectrometric conditions. Diminishing of this decelerating field by changing of the potential of the electron multiplier increased the overall sensitivity to negative ions...

  1. Ionizing device comprising a microchannel electron multiplier with secondary electron emission

    International Nuclear Information System (INIS)

    Chalmeton, Vincent.

    1974-01-01

    The present invention relates to a ionizing device comprising a microchannel electron multiplier involving secondary electron emission as a means of ionization. A system of electrodes is used to accelerate said electrons, ionize the gas and extract the ions from thus created plasma. Said ionizer is suitable for bombarding the target in neutron sources (target of the type of nickel molybdenum coated with tritiated titanium or with a tritium deuterium mixture) [fr

  2. Efficient design of multiplier-less digital channelizers using recombination non-uniform filter banks

    Directory of Open Access Journals (Sweden)

    Shaeen Kalathil

    2018-01-01

    Full Text Available A novel approach for the efficient realization of digital channelizers in software defined radios using recombination filter banks is proposed in this paper. Digital channelizer is the core of software defined radio. Computationally efficient design supporting multiple channels with different bandwidths and low complexity are inevitable requirements for the digital channelizers. Recombination filter banks method is used to obtain non-uniform filter banks with rational sampling factors, using a two stage structure. It consists of a uniform filter bank and trans-multiplexer. In this work, the uniform filter bank and trans-multiplexer are designed using cosine modulated filter banks. The prototype filter design is made simple, efficient and fast, using window method. The multiplier-less realization of recombination filter banks in the canonic signed digit space using nature inspired optimization algorithms, results in reduced implementation complexity.

  3. Sheath formation of a plasma containing multiply charged ions, cold and hot electrons, and emitted electrons

    International Nuclear Information System (INIS)

    You, H.J.

    2012-01-01

    It is quite well known that ion confinement is an important factor in an electron cyclotron resonance ion source (ECRIS) as it is closely related to the plasma potential. A model of sheath formation was extended to a plasma containing multiply charged ions (MCIs), cold and hot electrons, and secondary electrons emitted either by MCIs or hot electrons. In the model, a modification of the 'Bohm criterion' was given, the sheath potential drop and the critical emission condition were also analyzed. It appears that the presence of hot electrons and emitted electrons strongly affects the sheath formation so that smaller hot electrons and larger emission current result in reduced sheath potential (or floating potential). However the sheath potential was found to become independent of the emission current J when J > J c , (where J c is the critical emission current. The paper is followed by the associated poster

  4. Electronic de-multipliers II (ring-shape systems); Demultiplieurs electroniques II (systeme en anneau)

    Energy Technology Data Exchange (ETDEWEB)

    Raievski, V

    1948-09-01

    This report describes a new type of ring-shape fast electronic counter (de-multiplier) with a resolution capacity equivalent to the one made by Regener (Rev. of Scientific Instruments USA 1946, 17, 180-89) but requiring two-times less electronic valves. This report follows the general description of electronic de-multipliers made by J. Ailloud (CEA--001). The ring comprises 5 flip-flop circuits with two valves each. The different elements of the ring are calculated with enough details to allow the transfer of this calculation to different valve types. (J.S.)

  5. High dynamic range isotope ratio measurements using an analog electron multiplier

    Czech Academy of Sciences Publication Activity Database

    Williams, P.; Lorinčík, Jan; Franzreb, K.; Herwig, R.

    2013-01-01

    Roč. 45, č. 1 (2013), s. 549-552 ISSN 0142-2421 R&D Projects: GA MŠk ME 894 Institutional support: RVO:67985882 Keywords : Isotope ratios * electron multiplier * dynamic range Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.393, year: 2013

  6. Colliding beam studies of electron detachement from H- by multiply-charged ions

    International Nuclear Information System (INIS)

    Melchert, F.; Benner, M.; Kruedener, S.; Schulze, R.; Meuser, S.; Pfaff, S.; Petri, S.; Huber, K.; Salzborn, E.; Presnyakov, L.P.; Uskov, D.B.

    1993-01-01

    Employing the crossed-beams technique, we have investigated electron-detachment processes from H - in collisions with multiply-charged noble gas ions A q+ . Absolute cross sections for single- and double-electron removal have been measured at center-of-mass energies from 50 keV to 200 keV and charge states q up to 8

  7. Electron capture to autoionizing states of multiply charged ions

    International Nuclear Information System (INIS)

    Mack, E.M.

    1987-01-01

    The present thesis investigates electron capture reactions resulting from slow collisions (V q+ ) and neutral gas targets (B). The energy spectra of the emitted electrons are measured; detection angle is 50 0 . Mainly, autoionizing double capture resulting from collisions with two-electron targets (He, H 2 ) is studied; then, the emitted electrons stem from doubly excited projectile states. The projectiles used are bare C 6+ , the H-like and He-like ions of C, N and O, He-like Ne 8+ and Ne-like Ar 8+ . Excited metastable projectiles used are C 5+ (2s), He-like projectiles A q+ (1s2s 3 S) and Ar 8+ (...2p 5 3s). Comparison is made with the predictions of a recently proposed extended classical barrier model, that was developed in connection with the work. This model assumes sequential capture of the electrons ('two-step' process); it predicts the realized binding enegies of the captured electrons - which may be directly determined from the autoionization spectra using only the projectile charge, the ionization potentials of the target and the collision velocity as parameters. No adjustable parameter enters into the calculations. The term energies and decay modes of the highly excited product ions themselves are studied. Generally, the autoionizing decay of these states is found to proceed preferentially to the directly adjacent lower singly excited state. Experimental evidence is presented, that triply excited states decay by successive emission of two electrons, whenever this is energetically possible. Finally, the L-MM decay in few-electron systems is considered. 314 refs.; 96 figs.; 29 tabs

  8. Microchannel electron multiplier: improvement in gain performances and detection dynamics

    International Nuclear Information System (INIS)

    Audier, M.; Delmotte, J.C.; Boutot, J.P.

    1978-01-01

    The performances of an MCP are a function of its geometrical characteristics (diameter d and ratio 1/d of a channel, useful area) and of the applied voltage. Gain and mean output current are limited by saturation phenomena. By using a particular cascaded MCP's configuration, it is possible to simultaneously improve the gain, its associated fluctuations and the detection dynamics (detected level, counting rate). For gains 10 6 7 , the fluctuations, can be kept as low as 20% and an improvement by a factor > 10 can be obtained on the detection dynamics [fr

  9. Time resolution of Burle 85001 micro-channel plate photo-multipliers in comparison with Hamamatsu R2083

    Energy Technology Data Exchange (ETDEWEB)

    V. Baturin; V. Burkert; W. Kim; S. Majewsky; D. Nekrasov; K. Park; V. Popov; E. S. Smith; D. Son; S. S. Stepanyan; C. Zorn

    2005-06-01

    The CLAS detector will require improvements in its particle identification system to take advantage of the higher energies provided by the Jefferson Laboratory accelerator upgrade to 12 GeV. To this end, we have studied the timing characteristics of the micro-channel plate photo-multiplier 85001 from Burle, which can be operated in a high magnetic field environment. For reference and comparison, measurements were also made using the standard PMT R2083 from Hamamatsu using two timing methods. The cosmic ray method, which utilizes three identical scintillating counters 2cm x 3cm x 50cm with PMs at the ends, yields 59.1(0.7)ps. The location method of particles from radiative source with known coordinates has been used to compare timing resolutions of R2083 and Burle-85001. This ''coordinate method'' requires only one counter instrumented with two PMs and it yields 59.5(0.7)ps. For the micro-channel plate photomultiplier from Burle with an external amplification of 10 to the signals, the co ordinate method yields 130(4)ps. This method also makes it possible to estimate the number of primary photo-electrons.

  10. Electronic shell structure in multiply charged silver clusters

    International Nuclear Information System (INIS)

    Kandler, O.; Athanassenas, K.; Echt, O.; Kreisle, D.; Leisner, T.; Recknagel, E.

    1991-01-01

    Silver clusters are generated by standard laser vaporization technique and ionized via multiphoton ionization. Time-of-flight mass spectrometry reveals singly, doubly and triply charged clusters, Ag n z+ (z=1, 2, 3). The spectra show, for all charge states, intensity variations, indicating enhanced stabilities for cluster sizes with closed electronic configurations in accord with the spherical jellium model. (orig.)

  11. Studies of collision mechanisms in electron capture by slow multiply charged ions

    International Nuclear Information System (INIS)

    Gilbody, H B; McCullough, R W

    2004-01-01

    We review measurements based on translational energy spectroscopy which are being used to identify and assess the relative importance of the various collision mechanisms involved in one-electron capture by slow multiply charged ions in collisions with simple atoms and molecules

  12. Database for inelastic collisions of lithium atoms with electrons, protons, and multiply charged ions

    NARCIS (Netherlands)

    Schweinzer, J; Brandenburg, R; Bray, [No Value; Hoekstra, R; Aumayr, F; Janev, RK; Winter, HP

    New experimental and theoretical cross-section data for inelastic collision processes of Li atoms in the ground state and excited states (up to n = 4) with electrons, protons, and multiply charged ions have been reported since the database assembled by Wutte et al. [ATOMIC DATA AND NUCLEAR DATA

  13. Electron and X-ray emission in collisions of multiply charged ions and atoms

    International Nuclear Information System (INIS)

    Woerlee, P.H.

    1979-01-01

    The author presents experimental results of electron and X-ray emission following slow collisions of multiply charged ions and atoms. The aim of the investigation was to study the mechanisms which are responsible for the emission. (G.T.H.)

  14. Electron angular distribution axial channeling

    International Nuclear Information System (INIS)

    Khokonov, A.Kh.; Khokonov, M.Kh.

    1989-01-01

    Angular distributions of ultra-relativistic electrons are calculated in the assumption about presence of statistical equilibrium. Analysis is based on numerical solution of Fokker-Planck type kinetic equation. It is shown that in contrast to case of amorphous medium, the multiple scattering at axial channeling of negative particles results in self-focusing of the initial beam particles and due to it number of electrons moving at an angles to the chain, which are smaller, than critical angle of channeling, may increase by several times as compared to the initial one

  15. Electron loss from multiply protonated lysozyme ions in high energy collisions with molecular oxygen

    DEFF Research Database (Denmark)

    Hvelplund, P; Nielsen, SB; Sørensen, M

    2001-01-01

    We report on the electron loss from multiply protonated lysozyme ions Lys-Hn(n)+ (n = 7 - 17) and the concomitant formation of Lys-Hn(n+1)+. in high-energy collisions with molecular oxygen (laboratory kinetic energy = 50 x n keV). The cross section for electron loss increases with the charge state...... of the precursor from n = 7 to n = 11 and then remains constant when n increases further. The absolute size of the cross section ranges from 100 to 200 A2. The electron loss is modeled as an electron transfer process between lysozyme cations and molecular oxygen....

  16. Axial channeling of uttrarelativistic electrons

    Energy Technology Data Exchange (ETDEWEB)

    Telegin, V.I.; Khokonov, M.Kh. (Moskovskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Yadernoj Fiziki)

    1982-07-01

    The dynamics of motion of ultrarelativistic electrons under axial channeling conditions is investigated. The analysis is based on the solution of the kinetic equation obtained recently by Beloshitsky and Kumakhov. The particle dechanneling function is investigated as depending on the type of a crystal, particle energy and angle of entrance into the single crystal. It is found that for most of the beam the major diffusion mechanism is scattering by electrons. It is shown that an optimal depth range exists for which the fraction of channeled particles sharply increases at the expense of the quasi-channeled particles. In a number of cases the dechanneling length for crystals with high atomic numbers may be greater than that of light elements.

  17. Axial channeling of uttrarelativistic electrons

    International Nuclear Information System (INIS)

    Telegin, V.I.; Khokonov, M.Kh.

    1982-01-01

    The dynamics of motion of ultrarelativistic electrons under axial channeling conditions is investigated. The analysis is based on the solution of the kinetic equation obtained recently by Beloshitsky and Kumakhov. The particle dechanneling function is investigated as depending on the type of a crystal, particle energy and angle of entrance into the single crystal. It is found that for most of the beam the major diffusion mechanism is scattering by electrons. It is shown that an optimal depth range exists for which the fraction of channeled particles sharply increases at the expense of the quasi-channeled particles. In a number of cases the dechanneling length for crystals with high atomic numbers may be greater than that of light elements

  18. Indirect mechanisms in electron-impact ionization of multiply charged ions

    International Nuclear Information System (INIS)

    Phaneuf, R.A.; Gregory, D.C.

    1986-09-01

    The important role of indirect-ionization mechanisms in electron-impact ionization of multiply charged ions has been emphasized by some recent experiments conducted with the ORNL-ECR multicharged ion source. Illustrative examples of investigations of the Mg-isoelectronic and Fe-isonuclear sequences are presented and compared with the results of detailed theoretical calculations. New experimental data is also presented concerning the role of resonance effects in the ionization of Li-like O 5+ and Na-like Fe 15+ ions

  19. Development of a time projection chamber using gas electron multipliers (GEM-TPC)

    International Nuclear Information System (INIS)

    Oda, S.X.; Hamagaki, H.; Ozawa, K.; Inuzuka, M.; Sakaguchi, T.; Isobe, T.; Gunji, T.; Morino, Y.; Saito, S.; Yamaguchi, Y.L.; Sawada, S.; Yokkaichi, S.

    2006-01-01

    We developed a prototype time projection chamber using gas electron multipliers (GEM-TPC) for high energy heavy ion collision experiments. To investigate its performance, we conducted a beam test with three kinds of gases (Ar(90%)-CH 4 (10%), Ar(70%)-C 2 H 6 (30%) and CF 4 ). Detection efficiency of 99%, and spatial resolution of 79μm in the pad-row direction and 313μm in the drift direction were achieved. The test results show that the GEM-TPC meets the requirements for high energy heavy ion collision experiments. The configuration and performance of the GEM-TPC are described

  20. Axial channeling in electron diffraction

    International Nuclear Information System (INIS)

    Ichimiya, A.; Lehmpfuhl, G.

    1978-01-01

    Kossel patterns from Silicon and Niobium were obtained with a convergent electron beam. An intensity maximum in the direction of the zone axes [001] and [111] of Nb was interpreted as axial channeling. The intensity distribution in Kossel patterns was calculated by means of the Bloch wave picture of the dynamical theory of electron diffraction. Particularly zone axis patterns were calculated for different substance-energy combinations and they were compared with experimental observations. The intensity distribution in the calculated Kossel patterns was very sensitive to the model of absorption and it was found that a treatment of the absorption close to the model of Humphreys and Hirsch [Phil. Mag. 18, 115 (1968)] gave the best agreement with the experimental observations. Furthermore it is shown which Bloch waves are important for the intensity distribution in the Kossel patterns, how they are absorbed and how they change with energy. (orig.) [de

  1. Improving the resolution in soft X-ray emission spectrometers through photon-counting using an Electron Multiplying CCD

    International Nuclear Information System (INIS)

    Hall, D J; Soman, M; Tutt, J; Murray, N; Holland, A; Schmitt, T; Raabe, J; Strocov, V N; Schmitt, B

    2012-01-01

    In 2007, a study of back-illuminated Charge-Coupled Devices (CCDs) for soft X-ray photon detection demonstrated the improvements that could be brought over more traditional micro-channel plate detectors for X-ray spectrometers based on diffraction gratings and position sensitive detectors. Whilst the spatial resolution was reported to be improved dramatically, an intrinsic limit of approximately 25 micrometers was found due to the spreading of the charge cloud generated in the CCD across several pixels. To overcome this resolution limit, it is necessary to move away from the current integrated imaging methods and consider a photon-counting approach, recording the photon interaction locations to the sub-pixel level. To make use of photon-counting techniques it is important that the individual events are separable. To maintain the throughput of the spectrometer for high intensity lines, higher frame rates and therefore higher readout speeds are required. With CCD based systems, the increased noise at high readout speeds can limit the photon-counting performance. The Electron-Multiplying CCD shares a similar architecture with the standard CCD but incorporates a g ain register . This novel addition allows controllable gain to be applied to the signal before the read noise is introduced, therefore allowing individual events to be resolved above the noise even at much higher readout rates. In the past, the EM-CCD has only been available with imaging areas too small to be practical in soft X-ray emission spectrometers. The current drive for large area Electron-Multiplying CCDs is opening this technology to new photon-counting applications, requiring in-depth analysis of the processes and techniques involved. Early results indicate that through the introduction of photon-counting techniques the resolution in such systems can be dramatically improved.

  2. Coupled-Multiplier Accelerator Produces High-Power Electron Beams for Industrial Applications

    International Nuclear Information System (INIS)

    Hatridge, M.; McIntyre, P.; Roberson, S.; Sattarov, A.; Thomas, E.; Meitzler, Charles

    2003-01-01

    The coupled multiplier is a new approach to efficient generation of MeV d.c. power for accelerator applications. High voltage is produced by a series of modules, each of which consists of a high-power alternator, step-up transformer, and 3-phase multiplier circuit. The alternators are connected mechanically along a rotating shaft, and connected by insulating flexible couplers. This approach differs from all previous d.c. technologies in that power is delivered to the various stages of the system mechanically, rather than through capacitive or inductive electrical coupling. For this reason the capital cost depends linearly on required voltage and power, rather than quadratically as with conventional technologies. The CM technology enables multiple electron beams to be driven within a common supply and insulating housing. MeV electron beam is extremely effective in decomposing organic contaminants in water. A 1 MeV, 100 kW industrial accelerator using the CM technology has been built and is being installed for treatment of wastewater at a petrochemical plant

  3. Analysis of microwave amplifier and frequency multiplier tube with a multipactor electron gun

    International Nuclear Information System (INIS)

    Yokoo, Kuniyoshi; Ono, Shoichi; Tai, Dong-Zhe.

    1983-01-01

    The performance analysis was made for a multipactor microwave tube with the aim of realizing a microwave amplifier or a frequency multiplier tube with a multipactor cathode with high efficiency and high power. The possibility for producing the multipactor tube with high efficiency and high power was shown by using effectively the characteristics of the multipactor cathode which emits pulsed electron current with narrow band, synchronizing with high frequency period. As the operating conditions for the multipactor cathode, it was shown that the wide spacing of the cathode was needed for the operation in high operating power, and the narrow spacing was needed for the operation in high efficiency and for reducing power consumption. It was also shown that there were the best values of the high-frequency voltage for the cathode operation. The study by the simulation for the multipactor cathode and for the acceleration zone of electron current was also performed to examine the possible performance for a microwave amplifier and a frequency multiplier tube. For the use of the multipactor cathode with a spacing of 1 mm, the conversion efficiency for d. c. input power was 86, 56 and 31 % for the primary, the secondary and the tertiary harmonic wave amplifications, respectively. (Asami, T.)

  4. Plasma channels for electron beam transport

    International Nuclear Information System (INIS)

    Schneider, R.F.; Smith, J.R.; Moffatt, M.E.; Nguyen, K.T.; Uhm, H.S.

    1988-01-01

    In recent years, there has been much interest in transport of intense relativistic electron beams using plasma channels. These channels are formed by either: ionization of an organic gas by UV photoionization or electron impact ionization of a low pressure gas utilizing a low energy (typically several hundred volts) electron gun. The second method is discussed here. As their electron gun, the authors used a 12 volt lightbulb filament which is biased to -400 volts with respect to the grounded 15 cm diameter drift tube. The electrons emitted from the filament are confined by an axial magnetic field of --100 Gauss to create a plasma channel which is less than 1 cm in radius. The channel density has been determined with Langmuir probes and the resulting line densities were found to be 10 11 to 10 12 per cm. When a multi-kiloamp electron beam is injected onto this channel, the beam space charge will eject the plasma electrons leaving the ions behind to charge neutralize the electron beam, hence allowing the beam to propagate. In this work, the authors performed experimental studies on the dynamics of the plasma channel. These include Langmuir probe measurements of a steady state (DC) channel, as well as time-resolved Langmuir probe studies of pulsed channels. In addition they performed experimental studies of beam propagation in these plasma channels. Specifically, they observed the behavior of current transport in these channels. Detailed results of beam transport and channel studies are presented

  5. Detection of X-ray fluorescence of light elements by electron counting in a low-pressure gaseous electron multiplier

    International Nuclear Information System (INIS)

    Pansky, A.; Breskin, A.; Chechik, R.; Malamud, G.

    1992-12-01

    Ionization electrons deposited by soft X-rays in a low pressure (10 Torr) gas medium are efficiently counted by a multistage electron multiplier, providing an accurate measurement of the X-ray photon energy. Energy resolution of 56-28% FWHM were measured for X-rays of 110-676 eV, recording electrical induced charges or visible photons emitted during the avalanche process. It is demonstrated that a combined analysis of the number of electron trail length of an event, provides a powerful and competitive way of resolving ultra soft X-rays. We present the experimental technique, discuss the advantages and limitations of the Primary Electron Counter, and suggest ways to improve its performances. (authors)

  6. Removal of contaminating tritium and tritium pressure measurement by a secondary electron multiplier

    International Nuclear Information System (INIS)

    Ichimura, K.; Watanabe, K.; Nishizawa, K.; Fujita, J.

    1984-01-01

    A ceramic secondary electron multiplier (SEM), Ceratron, was used to study impairment of the SEM performance due to adsorbed tritium, its decontamination, and the applicability of the SEM to measure tritium pressure. The background level of the SEM increased significantly, up to its counting limit, due to tritium adsorption. Heating it to 300 0 C in vacuo and/or in the presence of reactive gases such as D 2 and CO at 1 x 10 -4 Pa was not effective to decontaminate the SEM, whereas photon irradiation was extremely powerful for the decontamination. The tritium (HT) pressure in a range of 1 x 10 -6 - 1 x 10 -3 Pa could be measured with no significant impairment of the SEM performance with the aid of photon irradiation. It is revealed that a particle flux as low as 1 particle/s will be able to measure in the presence of tritium if suitable photon sources are installed in the systems. (orig.)

  7. Gas electron multiplier (GEM) foil test, repair and effective gain calculation

    Science.gov (United States)

    Tahir, Muhammad; Zubair, Muhammad; Khan, Tufail A.; Khan, Ashfaq; Malook, Asad

    2018-06-01

    The focus of my research is based on the gas electron multiplier (GEM) foil test, repairing and effective gain calculation of GEM detector. During my research work define procedure of GEM foil testing short-circuit, detection short-circuits in the foil. Study different ways to remove the short circuits in the foils. Set and define the GEM foil testing procedures in the open air, and with nitrogen gas. Measure the leakage current of the foil and applying different voltages with specified step size. Define the Quality Control (QC) tests and different components of GEM detectors before assembly. Calculate the effective gain of GEM detectors using 109Cd and 55Fe radioactive source.

  8. High- and low-pressure operation of the gas electron multiplier

    International Nuclear Information System (INIS)

    Bondar, A.; Buzulutskov, A.; Shekhtman, L.; Sauli, F.

    1998-01-01

    We have studied the operation of the gas electron multiplier (GEM) in gas mixtures Xe-CO 2 , Ar-CO 2 and CH 4 at different pressures varying from 0.1 to 5 atm. In Ar- and Xe-based mixtures, the maximum GEM gain considerably decreases with pressure, from a few hundreds at 1 atm to below 10 at 5 atm. Combined gain of GEM and the micro-strip gas chamber (MSGC) can exceed values of 10000 at 1 atm and 100 at 5 atm. High GEM gains, of above 1000, were obtained in CH 4 at low pressures. We have observed the effect of the avalanche confinement in GEM micro-holes, resulting in violation of the pressure scaling and in the possibility of GEM operation in pure noble gases. (author)

  9. Performance test of a micro-pattern stereo detector with two gas electron multipliers

    International Nuclear Information System (INIS)

    Barvich, T.; Bluem, P.; Erdmann, M.; Fahrer, M.; Kaercher, K.; Kuehn, F.; Moermann, D.; Mueller, Th.; Neuberger, D.; Roederer, F.; Simonis, H.J.; Skiba, A.; Thuemmel, W.H.; Weiler, Th.; Weseler, S.

    2002-01-01

    We report on the performance of a large micro-pattern detector with two gas electron multiplier foils and a two-layer readout structure at ground potential. The two readout layers each have a 406 μm pitch and cross at an effective angle of 6.7 deg. . This structure allows for two orthogonal coordinates to be determined. Using a muon beam at CERN together with a silicon tracking system, the position resolutions of the two coordinates are measured to be 50 μm and 1 mm respectively (1 standard deviation). The muon detection efficiency for the two-dimensional space points reaches 96%. The detector was found to be well operational over a wide range in the settings of the different electrical fields

  10. Gas electron multiplier (GEM) operation with tissue-equivalent gases at various pressures

    International Nuclear Information System (INIS)

    Farahmand, M.; Bos, A.J.J.; Eijk, C.W.E. van

    2003-01-01

    We have studied the operation of two different Gas Electron Multiplier (GEM) structures in both methane and propane based Tissue-Equivalent (TE) gases at different pressures varying from 0.1 to 1 atm. This work was motivated to explore the possibility of using a GEM for a new type of Tissue Equivalent Proportional Counter. In methane based TE gas, a maximum safe GEM gain of 1.5x10 3 has been reached while in propane based TE gas this is 6x10 3 . These maxima have been reached at different gas pressures depending on GEM structure and TE gas. Furthermore, we observed a decrease of the GEM gain in time before it becomes stable. Charge up/polarisation effects can explain this

  11. Electronic Commerce and Retail Channel Substitution

    NARCIS (Netherlands)

    M.C.W. Janssen (Maarten); R. van der Noll

    2002-01-01

    textabstractWe analyze a market where firms compete in a conventional and an electronic retail channel. Consumers easily compare prices online, but some incur purchase uncertainties on the online channel. We investigate the market shares of the two retail channels and the prices that are charged. We

  12. Electron cyclotron resonance (E.C.R.) multiply charged ion sources

    International Nuclear Information System (INIS)

    Geller, R.

    1978-01-01

    High charge state ions can be produced by electron bombardment inside targets when the target electron density n (cm -3 ) multiplied by the ion transit time through the target tau (sec) is: n tau > 5.10 9 cm -3 sec. The relative velocity between electrons and ions determines the balance between stripping and capture i.e. the final ion charge state. (In a stripper foil fast ions interact with slow electrons involving typically n approximately 10 24 cm -3 , tau approximately 10 -14 sec). In the E.C.R. source a cold ion plasma created in a first stage diffuses slowly through a second stage containing a hot E.C.R. plasma with n > 3.10 11 cm -3 and tau > 10 -2 sec. Continuous beams of several μA of C 6+ N 7+ Ne 9+ A 11+ are extracted from the second stage with normalized emittances of approximately 0.5 π mm mrad. The absence of cathodes and plasma arcs makes the source very robust, reliable and well-fitted for cyclotron injection. A super conducting source is under development

  13. Effects of dislocations on electron channeling

    International Nuclear Information System (INIS)

    George, Juby; Pathak, A P

    2009-01-01

    The phenomenon of electron channeling in a crystal affected by dislocations is considered. Earlier we had considered the quantum aspects of the positron channeling in a crystal bent by dislocations where the effects of longitudinal motion of the particle were also considered along with the transverse motion. In this paper, the effective potential for the electron case is found for the two regions of dislocation-affected channel. There is considerable shift in the potential minima due to dislocations. The frequency and the corresponding spectrum of the channeling radiation due to electrons channeling through the perfect channel and the two regions of dislocation-affected channels are calculated. The spectral distribution of radiation intensity changes with the parameters of dislocation. The continuity of wavefunctions and their derivatives is used at the three boundaries and the reflection and transmission coefficients are found using these boundary conditions in the same way as in the positron case.

  14. Design of multiplier-less sharp non-uniform cosine modulated filter banks for efficient channelizers in software defined radio

    Directory of Open Access Journals (Sweden)

    Shaeen Kalathil

    2016-03-01

    Full Text Available Forthcoming software defined radios require filter banks which satisfy stringent specifications efficiently with low implementation complexity. Cosine modulated filter banks (CMFB have simple and efficient design procedure. The different wireless standards have different channel spacing or bandwidths and hence demand non-uniform decomposition of subbands. The non-uniform CMFB can be obtained from a uniform CMFB in a simple and efficient approach by merging the adjacent channels of the uniform CMFB. Very narrow transition width filters with low complexity can be achieved using frequency response masking (FRM filter as prototype filter. The complexity is further reduced by the multiplier-less realization of filter banks in which the least number of signed power of two (SPT terms is achieved by representing the filter coefficients using canonic signed digit (CSD representation and then optimizing using suitable modified meta-heuristic algorithms. Hybrid meta-heuristic algorithms are used in this paper. A hybrid algorithm combines the qualities of two meta-heuristic algorithms and results in improved performances with low implementation complexity. Highly frequency selective filter banks characterized by small passband ripple, narrow transition width and high stopband attenuation with non-uniform decomposition of subbands can be designed with least the implementation complexity, using this approach. A digital channelizer can be designed for SDR implementations, using the proposed approach. In this paper, the non-uniform CMFB is designed for various existing wireless standards.

  15. Multi-anode photon-multiplier readout electronics for the LHCb ring imaging Cherenkov detectors

    CERN Document Server

    Smale, N J

    2004-01-01

    A readout system for the Ring Imaging CHerenkov (RICH) detectors of the LHCb experiment has been developed. Two detector technologies for the measurement of Cherenkov photons are considered, the Multi-Anode Photo-Multiplier Tube (MAPMT) and the Hybrid Photon Detector (HPD), both of which meet the RICH requirements. The properties of the MAPMT are evaluated using a controlled single-photon source; a pixel-to-pixel gain variation of ~3 and a typical signal to noise of ~20 is measured. The relative tube efficiency is found to be reduced by ~26 % due to the detailed focusing structure of the MAPMT device. A radiation hard application-specific integrated circuit (ASIC) chip, the Beetle1.2MA0, has been developed to capture and store signals from a pair of MAPMTs. The Beetle1.2MA0 is built on the architecture of the Beetle family that was designed for silicon strip detectors, the difference being a modified front-end amplifier. The 128 input-channels of the Beetle1.2MA0 have a charge-sensitive pre-amplifier followed...

  16. Development of Gas Electron Multiplier(GEM) for digital radiographic system

    International Nuclear Information System (INIS)

    Moon, B. S.; Chung, C. E.; Lee, J. W.

    2000-04-01

    Two computer programs SHOWFIELD and IMAGEQUAL have been developed. SHOWFIELD is used to draw electric field lines for GEM detectors and IMAGEQUAL is used to study the spatial resolution of x-ray images. Various simulation runs have been carried out using EGS4 to study the characteristics of electrons generated by micro-channel plates and Ar, Xe gases. A prototype GEM detector was developed through this project. The GEM detector is composed of a pair of GEM plates, a micro-channel plate, readout circuit in a gas filled chamber. GEM plate were made in CERN to meet KAERI's design specification and the micro-channel plates were purchased from Proxitronic company

  17. Multicascade X-Ray Free-Electron Laser with Harmonic Multiplier and Two-Frequency Undulator

    Science.gov (United States)

    Zhukovsky, K. V.

    2018-06-01

    The feasibility of generation of powerful x-ray radiation by a cascade free-electron laser (FEL) with amplification of higher harmonics using a two-frequency undulator is studied. To analyze the FEL operation, a complex phenomenological single-pass FEL model is developed and used. It describes linear and nonlinear generation of harmonics in the FEL with seed laser that takes into account initial electron beam noise and describes all main losses of each harmonic in each FEL cascade. The model is also calibrated against and approved by the experimental FEL data and available results of three-dimensional numerical simulation. The electron beam in the undulator is assumed to be matched and focused, and the dynamics of power in the singlepass FEL with cascade harmonic multipliers is investigated to obtain x-ray laser radiation in the FEL having the shortest length, beam energy, and frequency of the seed laser as low as possible. In this context, the advantages of the two-frequency undulator used for generation of harmonics are demonstrated. The evolution of harmonics in a multicascade FEL with multiplication of harmonics is investigated. The operation of the cascade FEL at the wavelength λ = 1.14 nm, generating 30 MW already on 38 m with the seed laser operating at a wavelength of 11.43 nm corresponding to the maximal reflectivity of the multilayered mirror MoRu/Be coating is investigated. In addition, the operation of the multicascade FEL with accessible seed UVlaser operating at a wavelength of 157 nm (F2 excimer UV-laser) and electron beam with energy of 0.5 GeV is investigated. X-ray radiation simulated in it at the wavelength λ 3.9 nm reaches power of 50 MW already at 27 m, which is by two orders of magnitude shorter than 3.4 km of the x-ray FEL recently put into operation in Europe.

  18. Secondary scintillation yield from GEM and THGEM gaseous electron multipliers for direct dark matter search

    Science.gov (United States)

    Monteiro, C. M. B.; Fernandes, L. M. P.; Veloso, J. F. C. A.; Oliveira, C. A. B.; dos Santos, J. M. F.

    2012-07-01

    The search for alternatives to PMTs as photosensors in optical TPCs for rare event detection has significantly increased in the last few years. In particular, in view of the next generation large volume detectors, the use of photosensors with lower natural radioactivity, such as large area APDs or GM-APDs, with the additional possibility of sparse surface coverage, triggered the intense study of secondary scintillation production in micropattern electron multipliers, such as GEMs and THGEMs, as alternatives to the commonly used uniform electric field region between two parallel meshes. The much higher scintillation output obtained from the electron avalanches in such microstructures presents an advantage in those situations. The accurate knowledge of the amount of such scintillation is important for correct detector simulation and optimization. It will also serve as a benchmark for software tools developed and/or under development for the calculation of the amount of such scintillation.The secondary scintillation yield, or electroluminescence yield, in the electron avalanches of GEMs and THGEMs operating in gaseous xenon and argon has been determined for different gas pressures. At 1 bar, THGEMs deliver electroluminescence yields that are more than one order of magnitude higher when compared to those achieved in GEMs and two orders of magnitude when compared to those achieved in a uniform field gap. The THGEM electroluminescence yield presents a faster decrease with pressure when comparing to the GEM electroluminescence yield, reaching similar values to what is achieved in GEMs for xenon pressures of 2.5 bar, but still one order of magnitude higher than that produced in a uniform field gap. Another exception is the GEM operating in argon, which presents an electroluminescence yield similar to that produced in a uniform electric field gap, while the THGEM achieves yields that are more than one order of magnitude higher.

  19. Electronic trade effect of marketing channels

    OpenAIRE

    Lovreta Stipe; Stojković Dragan

    2009-01-01

    E-commerce has caused many significant changes in marketing channels. Consumers had obtained multiple benefits from e-commerce. In addition, it has increased the level of competition in marketing channels. However, the focus of this paper is multichannel strategy and integration of physical (store) and electronic marketing channels. E-commerce has induced dynamic development of multichannel strategy. This strategy has evolved as a consequence of multichannel consumer orientation. In developed...

  20. A Monte Carlo simulation of the microdosimetric response for thick gas electron multiplier

    International Nuclear Information System (INIS)

    Hanu, A.; Byun, S.H.; Prestwich, W.V.

    2010-01-01

    The neutron microdosimetric responses of the thick gas electron multiplier (THGEM) detector were simulated. The THGEM is a promising device for microdosimetry, particularly for measuring the dose spectra of intense radiation fields and for collecting two-dimensional microdosimetric distributions. To investigate the response of the prototype THGEM microdosimetric detector, a simulation was developed using the Geant4 Monte Carlo code. The simulation calculates the deposited energy in the detector sensitive volume for an incident neutron beam. Both neutron energy and angular responses were computed for various neutron beam conditions. The energy response was compared with the reported experimental microdosimetric spectra as well as the evaluated fluence-to-kerma conversion coefficients. The effects of using non-tissue equivalent materials were also investigated by comparing the THGEM detector response with the response of an ideal detector in identical neutron field conditions. The result of the angular response simulations revealed severe angular dependencies for neutron energies above 100 keV. The simulation of a modified detector design gave an angular response pattern close to the ideal case, showing a fluctuation of less than 10% over the entire angular range.

  1. Gas Electron Multipliers: Development of large area GEMs and spherical GEMs

    CERN Document Server

    Duarte Pinto, Serge; Brock, Ian

    2011-01-01

    Gaseous radiation detectors have been a crucial part of high-energy physics instrumentation since the 1960s, when the first multiwire proportional counters were built. In the 1990s the first micropattern gas detectors (MPGDs) saw the light; with sub-millimeter feature sizes these novel detectors were faster and more accurate than their predecessors. The gas electron multiplier (GEM) is one of the most successful of these technologies. It is a charge multiplication structure made from a copper clad polymer foil, pierced with a regular and dense pattern of holes. I will describe the properties and the application of GEMs and GEM detectors, and the research and development I have done on this technology. Two of the main objectives were the development of large area GEMs (~m^2) for particle physics experiments and GEMs with a spherical shape for x-ray or neutron diffraction detectors. Both have been realized, and the new techniques involved are finding their way to applications in research and industry.

  2. Gas electron multipliers. Development of large area GEMS and spherical GEMS

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Serge Duarte

    2011-08-15

    Gaseous radiation detectors have been a crucial part of high-energy physics instrumentation since the 1960s, when the first multiwire proportional counters were built. In the 1990s the first micropattern gas detectors (MPGDS) saw the light; with sub-millimeter feature sizes these novel detectors were faster and more accurate than their predecessors. The gas electron multiplier (GEM) is one of the most successful of these technologies. It is a charge multiplication structure made from a copper clad polymer foil, pierced with a regular and dense pattern of holes. I describe the properties and the application of GEMs and GEM. detectors, and the research and development I have done on this technology. Two of the main objectives were the development of large area GEMs ({proportional_to}m{sup 2}) for particle physics experiments and GEMs with a spherical shape for X-ray or neutron diffraction detectors. Both have been realized, and the new techniques involved are finding their way to applications in research and industry. (orig.)

  3. The current status of the Gas Electron Multiplier (GEM) research at Kasetsart University, Thailand

    Science.gov (United States)

    Kumpiranon, P.; Kulasri, K.; Rittirong, A.; Saenboonruang, K.

    2017-06-01

    During the past decade, Gas Electron Multiplier (GEM) detectors have been greatly developed and utilized in numbers of applications including advanced nuclear and particle researches, medical imaging, astrophysics, and neutron detection for national security. Our GEM research group at the Department of Applied Radiation and Isotopes, Faculty of Science, Kasetsart University, Thailand, realized in its excellent properties/potentials and started extensive researches on GEM detectors. To build a strong foundation on our research group, two 10 cm × 10 cm triple GEM detectors were characterized on their important properties including absolute gains and detection uniformity. Moreover, to widen applications of the GEM detector, our group had modified the GEM detector by introducing either solid or gaseous neutron converters to the detector so that the detector could effectively detect neutrons. These modifications included coating a thin film of 10B and natB to the GEM drift cathode for thermal neutron detection and flowing a gas mixture of He/CO2 (80:20 and 70:30) and C4H10/He/CO2 (7:70:23) for fast neutron detection. Results showed that the modified GEM-based neutron detector could detect both types of neutrons with different relative efficiencies and gains depending on thicknesses and types of neutron converters. This article discusses basic knowledge of the GEM detector, construction and testing procedures, results, and discussion.

  4. Gas electron multipliers: Development of large area GEMS and spherical GEMS

    International Nuclear Information System (INIS)

    Pinto, Serge Duarte

    2011-08-01

    Gaseous radiation detectors have been a crucial part of high-energy physics instrumentation since the 1960s, when the first multiwire proportional counters were built. In the 1990s the first micropattern gas detectors (MPGDS) saw the light; with sub-millimeter feature sizes these novel detectors were faster and more accurate than their predecessors. The gas electron multiplier (GEM) is one of the most successful of these technologies. It is a charge multiplication structure made from a copper clad polymer foil, pierced with a regular and dense pattern of holes. I describe the properties and the application of GEMs and GEM. detectors, and the research and development I have done on this technology. Two of the main objectives were the development of large area GEMs (∝m 2 ) for particle physics experiments and GEMs with a spherical shape for X-ray or neutron diffraction detectors. Both have been realized, and the new techniques involved are finding their way to applications in research and industry. (orig.)

  5. Dechanneling function for relativistic axially channeled electrons

    International Nuclear Information System (INIS)

    Muralev, V.A.; Telegin, V.I.

    1981-01-01

    Behaviour of the x(t) dechanneling function depending on the depth is theoretically studied. Theoretical consideration of x(t) for axial channeled relativistic electrons in anisotropic medium results in two-dimensional kinetic equation with mixed derivatives of the parabolic type. The kinetic equation in the approximation of the continuous Lindchard model for relativistic axial channeled electrons is numerically solved. The depth dependence of the x(t) dechanneling function is obtained [ru

  6. User's manual for EXALPHA (a code for calculating electronic properties of molecules). [Muscatel code, multiply scattered electron approximation

    Energy Technology Data Exchange (ETDEWEB)

    Jones, H.D.

    1976-06-01

    The EXALPHA procedures provide a simplified method for running the MUSCATEL computer code, which in turn is used for calculating electronic properties of simple molecules and atomic clusters, based on the multiply scattered electron approximation for the wave equations. The use of the EXALPHA procedures to set up a run of MUSCATEL is described.

  7. Critical voltage effects in electron channeling patterns

    International Nuclear Information System (INIS)

    Farrow, R.C.

    1984-01-01

    Electron channeling patterns were used to study critical voltage effects in the metals molybdenum and tungsten. The purpose was to characterize both theoretically and experimentally how a critical voltage will affect the channeling pattern line shapes. The study focused on the second order critical voltage that results from the degeneracy between the Bloch wave states of the (110) and (220) reflections. Theoretical (110) series electron channeling pattern line profiles were calculated using the dynamical theory of Hirsch and Humphreys (1970). A 10 beam dynamical electron diffraction calculation was performed (using complex Fourier lattice potentials) to generate Bloch wave coefficients, excitation amplitudes, and absorption coefficients needed for determining backscattering coefficients and subsequent backscattered electron intensities. The theoretical model is applicable to electron diffraction at all energies since no high energy approximation or perturbation method was used

  8. Coupled-channel calculations of partial capture cross sections in multiply charged ion collisions with hydrogen

    International Nuclear Information System (INIS)

    Hansen, J.P.; Taulbjerg, K.; University of Tennessee, Knoxville, Tennessee 37996)

    1989-01-01

    Partial cross sections for electron capture in 1--50-keV collisions of Ar 6+ and Ar 8+ with atomic hydrogen have been calculated using an atomic expansion including two complete principal shells of final states (n=4,5 for Ar 6+ and n=5,6 for Ar 8+ ). The qualitative structure of the results is in good accord with a reaction window picture. The results for Ar 6+ ions are in agreement with published experimental data when precaution is taken with respect to uncertainties in absolute normalization of the data and with respect to a proper analysis of translation energy spectra at lower impact energies. The limited experimental data for Ar 8+ do not agree with the present results

  9. A how-to approach for a 3D simulation of charge transfer characteristics in a gas electron multiplier (GEM)

    CERN Document Server

    Sharma, A

    1999-01-01

    In this paper a detailed description of how to simulate charge transfer processes in a gaseous device is presented, taking the gas electron multiplier (GEM) as an example. A 3-dimensional simulation of the electric field and avalanche is performed. Results on charge transport are compared to experiment and agree within experimental errors; the avalanche mechanism and positive ion feedback are studied. The procedures used in the simulation are described in detail, and program scripts are appended. (15 refs).

  10. Electronic trade effect of marketing channels

    Directory of Open Access Journals (Sweden)

    Lovreta Stipe

    2009-01-01

    Full Text Available E-commerce has caused many significant changes in marketing channels. Consumers had obtained multiple benefits from e-commerce. In addition, it has increased the level of competition in marketing channels. However, the focus of this paper is multichannel strategy and integration of physical (store and electronic marketing channels. E-commerce has induced dynamic development of multichannel strategy. This strategy has evolved as a consequence of multichannel consumer orientation. In developed economies, consumers are multichannel entities and active marketers aim to meet their requirements by creating multichannel offer.

  11. Cross-Calibration of Secondary Electron Multiplier in Noble Gas Analysis

    Science.gov (United States)

    Santato, Alessandro; Hamilton, Doug; Deerberg, Michael; Wijbrans, Jan; Kuiper, Klaudia; Bouman, Claudia

    2015-04-01

    The latest generation of multi-collector noble gas mass spectrometers has decisively improved the precision in isotopic ratio analysis [1, 2] and helped the scientific community to address new questions [3]. Measuring numerous isotopes simultaneously has two significant advantages: firstly, any fluctuations in signal intensity have no effect on the isotope ratio and secondly, the analysis time is reduced. This particular point becomes very important in static vacuum mass spectrometry where during the analysis, the signal intensity decays and at the same time the background increases. However, when multi-collector analysis is utilized, it is necessary to pay special attention to the cross calibration of the detectors. This is a key point in order to have accurate and reproducible isotopic ratios. In isotope ratio mass spectrometry, with regard to the type of detector (i.e. Faraday or Secondary Electron Multiplier, SEM), analytical technique (TIMS, MC-ICP-MS or IRMS) and isotope system of interest, several techniques are currently applied to cross-calibrate the detectors. Specifically, the gain of the Faraday cups is generally stable and only the associated amplifier must be calibrated. For example, on the Thermo Scientific instrument control systems, the 1011 and 1012 ohm amplifiers can easily be calibrated through a fully software controlled procedure by inputting a constant electric signal to each amplifier sequentially [4]. On the other hand, the yield of the SEMs can drift up to 0.2% / hour and other techniques such as peak hopping, standard-sample bracketing and multi-dynamic measurement must be used. Peak hopping allows the detectors to be calibrated by measuring an ion beam of constant intensity across the detectors whereas standard-sample bracketing corrects the drift of the detectors through the analysis of a reference standard of a known isotopic ratio. If at least one isotopic pair of the sample is known, multi-dynamic measurement can be used; in this

  12. Statistics of electron multiplication in a multiplier phototube; Iterative method; Estadistica de la multiplicacion de electrones en un fotomultiplicador: Metodos iterativos

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, J F; Grau, A

    1985-07-01

    In the present paper an iterative method is applied to study the variation of dynode response in the multiplier phototube. Three different situation are considered that correspond to the following ways of electronic incidence on the first dynode: incidence of exactly one electron, incidence of exactly r electrons and incidence of an average r electrons. The responses are given for a number of steps between 1 and 5, and for values of the multiplication factor of 2.1, 2.5, 3 and 5. We study also the variance, the skewness and the excess of jurtosis for different multiplication factors. (Author) 11 refs.

  13. Self-sputtering runaway in high power impulse magnetron sputtering: The role of secondary electrons and multiply charged metal ions

    International Nuclear Information System (INIS)

    Anders, Andre

    2008-01-01

    Self-sputtering runaway in high power impulse magnetron sputtering is closely related to the appearance of multiply charged ions. This conclusion is based on the properties of potential emission of secondary electrons and energy balance considerations. The effect is especially strong for materials whose sputtering yield is marginally greater than unity. The absolute deposition rate increases ∼Q 1/2 , whereas the rate normalized to the average power decreases ∼Q -1/2 , with Q being the mean ion charge state number

  14. Radiative electron capture by channeled ions

    International Nuclear Information System (INIS)

    Pitarke, J.M.; Ritchie, R.H.; Tennessee Univ., Knoxville, TN

    1989-01-01

    Considerable experimental data have been accumulated relative to the emission of photons accompanying electron capture by swift, highly stripped atoms penetrating crystalline matter under channeling conditions. Recent data suggest that the photon energies may be less than that expected from simple considerations of transitions from the valence band of the solid to hydrogenic states on the moving ion. We have studied theoretically the impact parameter dependence of the radiative electron capture (REC) process, the effect of the ion's wake and the effect of capture from inner shells of the solid on the photon emission probability, using a statistical approach. Numerical comparisons of our results with experiment are made. 13 refs., 6 figs

  15. Multiply ionization of diethyl ether clusters by 532 nm nanosecond laser: The influence of laser intensity and the electron energy distribution

    International Nuclear Information System (INIS)

    Zhang Nazhen; Wang Weiguo; Zhao Wuduo; Han Fenglei; Li Haiyang

    2010-01-01

    Graphical abstract: The formation mechanism for multiply charged ions (C q+ and O q+ (q = 2-4)) were investigated experimentally and theoretically using a dual polarity time-of-flight mass spectrometer when diethyl ether clusters interacted with nanosecond laser pulse. - Abstract: The formation mechanism for multiply charged ions (C q+ and O q+ (q = 2-4)) were investigated using a dual polarity time-of-flight mass spectrometer when diethyl ether clusters interacted with nanosecond laser pulse. The signal intensity of multiply charged ions and electron energy was measured experimentally. It was shown that the intensity of multiply charged ions increased about 50 times when laser intensity increased from 7.6 x 10 9 to 7.0 x 10 10 W/cm 2 , then saturated as laser intensity increased further. It is interesting that the evolution of the mean value of electron energy was same to that of multiply charged ions. The theoretical calculation showed the ionization potential of atomic ions could be significantly decreased due to the effect of Coulomb screening especially at low laser intensity. It indicated that the electron ionization combined with Coulomb screening effect could explain the production of multiply charged ions in nanosecond laser field.

  16. Electron loss process and cross section of multiply charged ions by neutral atoms

    International Nuclear Information System (INIS)

    Karashima, S.; Watanabe, T.

    1985-01-01

    The significance of experimental and theoretical results on the electron loss and capture of ions in matter plays an important role in the charge equilibrium problems of fusion plasma physics and of accelerator physics. In the report, we calculate electron stripping cross section by using the binary encounter approximation (BEA). Our treatment of the electron loss process is based on BEA, in which the nucleus of B screened by the surrounding electrons collides with electrons in the ion A sup(q+). The basic approximation in EBA is that the ion interacts with only one electron or nucleus of the target atom at a time. In the calculation for Li sup(2+) + H, we have found that EBA will give approximately reliable results. (Mori, K.)

  17. Gaseous electron multiplier-based soft x-ray plasma diagnostics development: Preliminary tests at ASDEX Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Chernyshova, M., E-mail: maryna.chernyshova@ipplm.pl; Malinowski, K.; Czarski, T.; Kowalska-Strzęciwilk, E. [Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw (Poland); Wojeński, A.; Poźniak, K. T.; Kasprowicz, G.; Krawczyk, R.; Kolasiński, P.; Zabołotny, W.; Zienkiewicz, P. [Institute of Electronic Systems, Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warsaw (Poland); Vezinet, D.; Herrmann, A. [Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Mazon, D.; Jardin, A. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)

    2016-11-15

    A Gaseous Electron Multiplier (GEM)-based detector is being developed for soft X-ray diagnostics on tokamaks. Its main goal is to facilitate transport studies of impurities like tungsten. Such studies are very relevant to ITER, where the excessive accumulation of impurities in the plasma core should be avoided. This contribution provides details of the preliminary tests at ASDEX Upgrade (AUG) with a focus on the most important aspects for detector operation in harsh radiation environment. It was shown that both spatially and spectrally resolved data could be collected, in a reasonable agreement with other AUG diagnostics. Contributions to the GEM signal include also hard X-rays, gammas, and neutrons. First simulations of the effect of high-energy photons have helped understanding these contributions.

  18. Electron beam effects on the spectroscopy of multiply charged ions in plasma focus experiments

    International Nuclear Information System (INIS)

    Abdallah, J.; Clark, R.E.H.; Faenov, A.Y.; Karpinski, L.; Pikuz, S.A.; Romanova, V.M.; Sadowski, M.; Scholz, M.; Szydlowski, A.

    1999-01-01

    Argon-hydrogen mixture plasma focus experiments performed at the Warsaw Institute of Plasma Physics and Laser Microfusion show detailed space resolved spectra for Ar K-shell satellite lines up to F-like Ar and K-alpha of Ar. These transitions originating from autoionizing levels are caused by collisions of ions with the energetic electron beams which are created by the constrictions of the plasma column due to the development of magnetohydrodynamic instabilities. A collisional-radiative model was constructed using a non-Maxwellian electron energy distribution consisting of a thermal Maxwellian part plus a Gaussian part to represent the high-energy electron beam. The shapes of the observed satellite structures are consistent with the calculated spectrum for electron temperatures between 20 and 230 eV, and beam densities of about 10 -3 times the plasma electron density. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  19. Electron beam effects on the spectroscopy of multiply charged ions in plasma focus experiments

    Energy Technology Data Exchange (ETDEWEB)

    Abdallah, J. [UCLA Plasma Physics Laboratory, Los Angeles, CA (United States); Clark, R.E.H. [Los Alamos National Laboratory, Los Alamos, NM (United States); Faenov, A.Y. [MISDC, NPO ' VNIIFTRI' , Mendeleevo, Moscow region, 141570 (Russian Federation); Karpinski, L. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Pikuz, S.A.; Romanova, V.M. [P. N. Lebedev Physical Institute, Moscow (Russian Federation); Sadowski, M. [Soltan Institute for Nuclear Studies, Swierk (Poland); Scholz, M.; Szydlowski, A. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland)

    1999-05-01

    Argon-hydrogen mixture plasma focus experiments performed at the Warsaw Institute of Plasma Physics and Laser Microfusion show detailed space resolved spectra for Ar K-shell satellite lines up to F-like Ar and K-alpha of Ar. These transitions originating from autoionizing levels are caused by collisions of ions with the energetic electron beams which are created by the constrictions of the plasma column due to the development of magnetohydrodynamic instabilities. A collisional-radiative model wasconstructed using a non-Maxwellian electron energy distribution consisting of a thermal Maxwellian part plus a Gaussian part to represent the high-energy electron beam. The shapes of the observed satellite structures are consistent with the calculated spectrum for electron temperatures between 20 and 230 eV, and beam densities of about 10{sup -3} times the plasma electron density. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  20. Study of spatial resolution of coordinate detectors based on Gas Electron Multipliers

    Science.gov (United States)

    Kudryavtsev, V. N.; Maltsev, T. V.; Shekhtman, L. I.

    2017-02-01

    Spatial resolution of GEM-based tracking detectors is determined in the simulation and measured in the experiments. The simulation includes GEANT4 implemented transport of high energy electrons with careful accounting of atomic relaxation processes including emission of fluorescent photons and Auger electrons and custom post-processing with accounting of diffusion, gas amplification fluctuations, distribution of signals on readout electrodes, electronics noise and particular algorithm of final coordinate calculation (center of gravity). The simulation demonstrates that the minimum of spatial resolution of about 10 μm can be achieved with a gas mixture of Ar -CO2 (75-25 %) at a strips pitch from 250 μm to 300 μm. At a larger pitch the resolution quickly degrades reaching 80-100 μm at a pitch of 460-500 μm. Spatial resolution of low-material triple-GEM detectors for the DEUTERON facility at the VEPP-3 storage ring is measured at the extracted beam facility of the VEPP-4 M collider. One-coordinate resolution of the DEUTERON detector is measured with electron beam of 500 MeV, 1 GeV and 3.5 GeV energies. The determined value of spatial resolution varies in the range from approximately 35 μm to 50 μm for orthogonal tracks in the experiments.

  1. Electron capture and ionization in collisions of multiply charged ions with H(2s)

    International Nuclear Information System (INIS)

    Errea, L F; Guzman, F; Illescas, Clara; Mendez, L; Pons, B; Riera, A; Suarez, J

    2007-01-01

    We present total cross sections for electron capture and ionization in collisions of B 5+ and Ne 10+ with H(2s), calculated using two methods: the semiclassical close-coupling molecular formalism and the eikonal-CTMC method. We have evaluated partial cross sections for capture into excited n-levels, required in plasma diagnostics

  2. Dictionary Indexing of Electron Channeling Patterns.

    Science.gov (United States)

    Singh, Saransh; De Graef, Marc

    2017-02-01

    The dictionary-based approach to the indexing of diffraction patterns is applied to electron channeling patterns (ECPs). The main ingredients of the dictionary method are introduced, including the generalized forward projector (GFP), the relevant detector model, and a scheme to uniformly sample orientation space using the "cubochoric" representation. The GFP is used to compute an ECP "master" pattern. Derivative free optimization algorithms, including the Nelder-Mead simplex and the bound optimization by quadratic approximation are used to determine the correct detector parameters and to refine the orientation obtained from the dictionary approach. The indexing method is applied to poly-silicon and shows excellent agreement with the calibrated values. Finally, it is shown that the method results in a mean disorientation error of 1.0° with 0.5° SD for a range of detector parameters.

  3. Simulation and Digitization of a Gas Electron Multiplier Detector Using Geant4 and an Object-Oriented Digitization Program

    Science.gov (United States)

    McMullen, Timothy; Liyanage, Nilanga; Xiong, Weizhi; Zhao, Zhiwen

    2017-01-01

    Our research has focused on simulating the response of a Gas Electron Multiplier (GEM) detector using computational methods. GEM detectors provide a cost effective solution for radiation detection in high rate environments. A detailed simulation of GEM detector response to radiation is essential for the successful adaption of these detectors to different applications. Using Geant4 Monte Carlo (GEMC), a wrapper around Geant4 which has been successfully used to simulate the Solenoidal Large Intensity Device (SoLID) at Jefferson Lab, we are developing a simulation of a GEM chamber similar to the detectors currently used in our lab. We are also refining an object-oriented digitization program, which translates energy deposition information from GEMC into electronic readout which resembles the readout from our physical detectors. We have run the simulation with beta particles produced by the simulated decay of a 90Sr source, as well as with a simulated bremsstrahlung spectrum. Comparing the simulation data with real GEM data taken under similar conditions is used to refine the simulation parameters. Comparisons between results from the simulations and results from detector tests will be presented.

  4. Effect of an electron beam generated in an X-pinch plasma on the structure of the K spectra of multiply charged ions

    International Nuclear Information System (INIS)

    Pikuz, S.A.; Shelkovenko, T.A.; Ramanova, V.M.; Abdallah, J. Jr.; Csanak, G.; Clark, R.E.H.; Faenov, A.Ya.; Skobelev, I.Yu.; Hammer, D.A.

    1997-01-01

    The first experimental studies of an electron beam generated in an X pinch on the XP machine (Cornell University, USA) and the BIN machine (P. N. Lebedev Physical Institute, Russian Academy of Sciences) are reported. It is shown that it is possible in an X pinch to isolate the effect of a plasma-generated electron beam on the multiply charged ion radiation. The intensities of the satellite lines corresponding to Li-, Be-, B-, and C-like ions are calculated for the Al spectrum on the basis of a collisional-radiative model with a non-Maxwellian electron distribution in the plasma. The effect of an electron beam on the multiply charged light ion radiation in an X-pinch plasma is demonstrated. Comparing our calculations with the experimental spectra, we conclude that the present model can be used to estimate the electron beam intensity

  5. Optimizing low-light microscopy with back-illuminated electron multiplying charge-coupled device: enhanced sensitivity, speed, and resolution.

    Science.gov (United States)

    Coates, Colin G; Denvir, Donal J; McHale, Noel G; Thornbury, Keith D; Hollywood, Mark A

    2004-01-01

    The back-illuminated electron multiplying charge-coupled device (EMCCD) camera is having a profound influence on the field of low-light dynamic cellular microscopy, combining highest possible photon collection efficiency with the ability to virtually eliminate the readout noise detection limit. We report here the use of this camera, in 512 x 512 frame-transfer chip format at 10-MHz pixel readout speed, in optimizing a demanding ultra-low-light intracellular calcium flux microscopy setup. The arrangement employed includes a spinning confocal Nipkow disk, which, while facilitating the need to both generate images at very rapid frame rates and minimize background photons, yields very weak signals. The challenge for the camera lies not just in detecting as many of these scarce photons as possible, but also in operating at a frame rate that meets the temporal resolution requirements of many low-light microscopy approaches, a particular demand of smooth muscle calcium flux microscopy. Results presented illustrate both the significant sensitivity improvement offered by this technology over the previous standard in ultra-low-light CCD detection, the GenIII+intensified charge-coupled device (ICCD), and also portray the advanced temporal and spatial resolution capabilities of the EMCCD. Copyright 2004 Society of Photo-Optical Instrumentation Engineers.

  6. Preliminary results of the Gas Electron Multiplier (GEM) as real-time beam monitor in hadron therapy

    Energy Technology Data Exchange (ETDEWEB)

    Aza, E., E-mail: eleni.aza@cern.ch [CERN, Geneva 23, 1211 Geneva (Switzerland); AUTH, Department of Physics, 54124 Thessaloniki (Greece); Ciocca, M. [Fondazione CNAO, Strada Campeggi 53, 27100 Pavia (Italy); Murtas, F. [CERN, Geneva 23, 1211 Geneva (Switzerland); LNF-INFN, Via Fermi 40, 00044 Frascati (Italy); Puddu, S. [CERN, Geneva 23, 1211 Geneva (Switzerland); AEC-LHEP, University of Bern, Sidlerstrasse 5, 3012 Bern (Switzerland); Pullia, M. [Fondazione CNAO, Strada Campeggi 53, 27100 Pavia (Italy); Silari, M. [CERN, Geneva 23, 1211 Geneva (Switzerland)

    2017-01-01

    The use of proton and carbon ion beams in cancer therapy (also known as hadron therapy) is progressively growing worldwide due to their improved dose distributions, sparing of healthy tissues and (for carbon ions) increased radiobiological effectiveness especially for radio-resistant tumours. Strict Quality Assurance (QA) protocols need to be followed for guaranteeing the clinical beam specifications. The aim of this study was to assess the performance of a gaseous detector based on the Gas Electron Multiplier (GEM) technology for measuring the beam spot dimensions and the homogeneity of the scanned irradiation field, which are daily QA tasks commonly performed using radiochromic films. Measurements performed at the National Centre for Oncological Hadron Therapy (CNAO) in Pavia (Italy) showed that the detector is able to monitor the 2D beam image on-line with a pad granularity of 2 mm and a response proportional to the number of delivered particles. The dose homogeneity was measured with low deviation from the results obtained with radiochromic films.

  7. Mass spectrometric determination of magnesium isotopic ratios and its corrections for electron multiplier discrimination and mass fractionation

    International Nuclear Information System (INIS)

    Deng Zhongguo

    1989-01-01

    The mass spectrometric determination of magnesium isotopic ratios by the use of uranyl nitrate added to magnesium samples to act as a binding agent is reported. Prebaking empty filaments and preheating filaments with deposited magnesium samples on its surface in a vacuum are employed to reduce the Na signal from the thenium-ribbon. Methods for correcting magnesium isotopic ratios for electron multiplier discrimination and mass fractionation are described in detail. The results of the determination of natural magnesium isotopic ratios are 25 Mg/ 24 Mg = 0.12660 (1±0.01%) and 26 Mg/ 24 Mg = 0.13938 (1±0.10%). The magnesium isotopic ratios of rich - 26 Mg-2 sample and rich- 25 Mg-1 sample are 24 Mg/ 26 Mg = 0.003463 (1±0.2%), 25 Mg/ 26 Mg = 0.001656 (±0.2%) and 24 Mg/ 25 Mg = 0.006716 (1±0.2%), 26 Mg/ 25 Mg = 0.007264 (1±0.2%) respectively

  8. Test beam studies of Gas Electron Multiplier (GEM) detectors for the upgrade of CMS endcap muon system

    CERN Document Server

    Sharma, Ram Krishna

    2017-01-01

    The High Luminosity LHC (HL-LHC) will provide exceptional high instantaneous and integrated luminosity. The forward region $\\mid \\eta \\mid \\geq 1.5$ of the CMS detector will face extremely high particle rates in tens of $KHz/cm^{2}$ and hence it will affect the momentum resolution and longevity of the muon detectors. To overcome these issues the CMS collaboration has decided to install new large size rate capable Triple Gas Electron Multiplier (GEM) detectors in the forward region of CMS muon system. The first set of Triple GEM detectors will be installed in the GE1/1 region $(1.5 \\leq \\eta \\leq 2.2)$ of muon endcap during the LS2 of the LHC and the next one will be installed in the GE2/1 region $(1.6 \\leq \\eta \\leq 2.5)$, during the LS3. Towards this goal, full-size CMS Triple GEM prototype chambers have been fabricated and put under the test beam at the CERN SPS test beam facility. The GEM detectors were operated with two gas mixtures $Ar/CO_{2}$ (70/30) and $Ar/CO_{2}/CF_{4}$ (40/15/45). In 2014 and 2016, ...

  9. Modulated electron-multiplied fluorescence lifetime imaging microscope: all-solid-state camera for fluorescence lifetime imaging.

    Science.gov (United States)

    Zhao, Qiaole; Schelen, Ben; Schouten, Raymond; van den Oever, Rein; Leenen, René; van Kuijk, Harry; Peters, Inge; Polderdijk, Frank; Bosiers, Jan; Raspe, Marcel; Jalink, Kees; Geert Sander de Jong, Jan; van Geest, Bert; Stoop, Karel; Young, Ian Ted

    2012-12-01

    We have built an all-solid-state camera that is directly modulated at the pixel level for frequency-domain fluorescence lifetime imaging microscopy (FLIM) measurements. This novel camera eliminates the need for an image intensifier through the use of an application-specific charge coupled device design in a frequency-domain FLIM system. The first stage of evaluation for the camera has been carried out. Camera characteristics such as noise distribution, dark current influence, camera gain, sampling density, sensitivity, linearity of photometric response, and optical transfer function have been studied through experiments. We are able to do lifetime measurement using our modulated, electron-multiplied fluorescence lifetime imaging microscope (MEM-FLIM) camera for various objects, e.g., fluorescein solution, fixed green fluorescent protein (GFP) cells, and GFP-actin stained live cells. A detailed comparison of a conventional microchannel plate (MCP)-based FLIM system and the MEM-FLIM system is presented. The MEM-FLIM camera shows higher resolution and a better image quality. The MEM-FLIM camera provides a new opportunity for performing frequency-domain FLIM.

  10. Muon Chamber Endcap Upgrade of the CMS Experiment with Gas Electron Multiplier (GEM) Detectors and their Performance

    CERN Document Server

    Gola, Mohit

    2017-01-01

    As the CERN LHC is heading towards a high luminosity phase a very high flux is expected in the endcaps of the CMS Detector. The presence of muons in collision events can be due to rare or new physics so it is important to maintain the high trigger efficiency of the CMS muon system. The CMS Collaboration has proposed to instrument the high-eta region (1.6 lt IetaI lt 2.2) of the muon endcaps with Gas Electron Multiplier (GEM) detectors, referred to as GE1/1 chambers, during the LS2. This technology will help in maintaining optimum trigger performance with maximum selection efficiency of muons even in a high flux environment. We describe plans for a Slice Test to installa few GE1/1 chambers covering 50 degrees in azimuthal angle within the CMS detector in 2017, with subsequent operation during the current Run 2 of the LHC. We show the performance of the GE1/1 chambers to be installed during the slice test, specifically GEM foil leakage currents, chamber gas volume integrity, high voltage circuit performanc...

  11. Radiation at planar channeling of relativistic electrons in thick crystals

    International Nuclear Information System (INIS)

    Baier, V.N.; Katkov, V.M.; Strakhovenko, V.M.

    1983-01-01

    The distribution kinetics with respect to the transverse energy at electron channeling is discussed. The asymptotic expressions for the radiation intensity into a given collimator at electron channeling in thick crystals are derived. An optimal thickness at which the radiation output is maximal is found. The spectral distribution of the radiation intensity is analysed for the case of a single diamond crystal. (author)

  12. Stresses in the foil of an electron accelerator extraction channel

    International Nuclear Information System (INIS)

    Abroyan, M.A.; Makarenko, T.I.; Tokmakov, I.L.

    1983-01-01

    Stresses in the foil of an electron accelerator extraction channel are assessed with account of contributions of thermal expansion and stress concentrations during switchings. Optimization of extraction grid parameters of the electron accelerator extraction channel and choice of foil material for high current electron beam is conducted. It is suggested that an extraction grid with circular cells and Al-Mg foil should be used. A simple formula applicable for design calculations is proposed for evaluation of stress concentration coefficient during phase switchings

  13. Ultrarelativistic electron and positron radiation in planar channeling

    International Nuclear Information System (INIS)

    Kalashnikov, N.P.; Olchack, A.S.

    1980-01-01

    The coherent electromagnetic radiation from channeling electrons and positrons is given by similar expression. However for the channeling positrons the close collisions are suppressed due to the fact that the positron wave function is exponentially small near the atoms of the crystal lattice. It follows that the coherent bremsstrahlung decreases for the channeling positrons. We have investigated the ultrarelativistic channeling electron and positron radiations, connected with the electromagnetic transitions from the continuum spectrum states to the quasi-bound spectrum states and between the different quasi-bound spectrum states. The radiation probabilities are calculated by using the model continuum planar potential. It is shown that the radiation from the channeling electrons is several orders of magnitude larger than the positron radiation, while the electron and positron radiation have similar characteristics such as frequency limitation and angular distribution of the radiation. (orig.)

  14. Multiplying Money

    Directory of Open Access Journals (Sweden)

    Garry Jacobs

    2013-05-01

    Full Text Available This article is not a comprehensive factual history of money as an economic instrument. It aims rather to present an essential psychological history of the power of money as a social organization or social technology. It explores the catalytic role of money in the development of society and its ever-increasing capacity for accomplishment in both economic and non-economic fields. This perspective focuses attention on the unutilized potential for harnessing the social power of money for promoting full employment, global development and human welfare. The title ‘multiplying money’ is intended to convey the idea that this untapped potential is exponential in nature. In order to recognize it, some fundamental misconceptions about the nature of money, how it is created and on what it is based need to be examined. This is the second article in a series.

  15. Limitation of secondary electron multiplier non-linearity on accurate U-Th isotopic determination by MC-ICP-MS

    Science.gov (United States)

    Shen, C.; Wu, C.; Gallet, S.; Cheng, H.; Edwards, R.; Hsieh, Y.; Lin, K.

    2008-12-01

    Contemporary multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS) with discrete dynode secondary electron multipliers (SEMs) can offer U-Th isotopic determinations with subpermil-permil- level precision in femtogram quantities. However, accurate isotopic measurement requires fully understanding SEM mass and intensity biases. In additional to dead-time effect, Richter et al (2001, Int. J. Mass Spectrom., 206, 105-127) reported a nonlinearity on SEMs produced by ETP and MasCom for count rates > 20 thousand counts per second (cps). We evaluated the possible biases for ion beams of 500- 1,600,000 cps on a latest MasCom SEM, SEV TE-Z/17, with more effective ion optical acceptance area (>50%) and better peak shape than previous models, used in a MC-ICP-MS, Thermo Fisher NEPTUNE. With the retarding potential quadruple lens (RPQ) turned off, ion beam intensity can be biased by only dead- time effect, which can be precisely corrected online or offline. With the RPQ on, two additional biases, an exponential-like increase of ion beam intensity from 100-100,000 s cps and an apparent dead-time effect (-2 to 2 ns) at high count rates, are observed. They are likely caused by the slightly defocused ions with a wide kinetic energy spread of ~5 eV, 10 times worse than that with thermal source, passing through the RPQ lens to the SEM, which is installed behind the focal plane. Fortunately, the two biases, which are stable during the daily measurements with the same settings of inlet system, source lenses, zoom optics, and RPQ, can be corrected effectively offline to earn accurate U-Th isotopic measurement.

  16. Secondary electron emission induced by channeled relativistic electrons in a (1 1 0) Si crystal

    International Nuclear Information System (INIS)

    Korotchenko, K.B.; Kunashenko, Yu P.; Tukhfatullin, T.A.

    2012-01-01

    A new effect that accompanies electrons channeled in a crystal is considered. This phenomenon was previously predicted was called channeling secondary electron emission (CSEE). The exact CSEE cross-section on the basis of using the exact Bloch wave function of electron channeled in a crystal is obtained. The detailed investigation of CSEE cross-section is performed. It is shown that angular distribution of electrons emitted due to CSEE has a complex form.

  17. Molecular type channeling of relativistic electrons in crystals

    International Nuclear Information System (INIS)

    Vyatkin, E.G.; Filimonov, Yu.M.; Taratin, A.M.; Vorobiev, S.A.

    1983-01-01

    Channeling of relativistic electrons in direction in a diamond crystal and the channeling radiation spectra are investigated using computer simulation by the binary collision model and using the model of a continuum potential of the atomic rows. In a computer experiment the atomic- and molecular-type states of channeled elcetrons are revealed, and the orientational dependence of the electron trapping probability in these states is obtained. The peculiarities revealed of the angular distributions and radiation spectra of electrons in the molecular-type states allow to discover these states in the experiment. (author)

  18. Multiplying dimensions

    CERN Multimedia

    2013-01-01

    A few weeks ago, I had a vague notion of what TED was, and how it worked, but now I’m a confirmed fan. It was my privilege to host CERN’s first TEDx event last Friday, and I can honestly say that I can’t remember a time when I was exposed to so much brilliance in such a short time.   TEDxCERN was designed to give a platform to science. That’s why we called it Multiplying Dimensions – a nod towards the work we do here, while pointing to the broader importance of science in society. We had talks ranging from the most subtle pondering on the nature of consciousness to an eighteen year old researcher urging us to be patient, and to learn from our mistakes. We had musical interludes that included encounters between the choirs of local schools and will.i.am, between an Israeli pianist and an Iranian percussionist, and between Grand Opera and high humour. And although I opened the event by announcing it as a day off from physics, we had a quite brill...

  19. Electronic government: Rethinking channel management strategies

    NARCIS (Netherlands)

    Ebbers, Wolfgang E.; Pieterson, Willem Jan; Noordman, H.N.

    2008-01-01

    This article explores how an alternative multichannel management strategy can improve the way governments and citizens interact. Improvement is necessary because, based on empirical data from various sources, the conclusion can be drawn that there is a gap between the communication channels

  20. Single-electron quantum tomography in quantum Hall edge channels

    International Nuclear Information System (INIS)

    Grenier, Ch; Degiovanni, P; Herve, R; Bocquillon, E; Parmentier, F D; Placais, B; Berroir, J M; Feve, G

    2011-01-01

    We propose a quantum tomography protocol to measure single-electron coherence in quantum Hall edge channels, and therefore access for the first time the wavefunction of single-electron excitations propagating in ballistic quantum conductors. Its implementation would open the way to quantitative studies of single-electron decoherence and would provide a quantitative tool for analyzing single- to few-electron sources. We show how this protocol could be implemented using ultrahigh-sensitivity noise measurement schemes.

  1. Experimental study of intensive electron beam scattering in melting channel

    International Nuclear Information System (INIS)

    Balagura, V.S.; Kurilko, V.I.; Safronov, B.G.

    1988-01-01

    Multiple scattering of an intensive electron beam at 28 keV energy passing through a melting channel in iron targets is experimentally studied. The dependence of scattering on the melting current value is established. The material density in the channel on the basis of the binary collision method is evaluated. It is shown that these density values are of three orders less than the estimations made on the basis of the data on energy losses of electrons in the channel. 6 refs.; 4 figs

  2. Relativistic electron-beam transport in curved channels

    International Nuclear Information System (INIS)

    Vittitoe, C.N.; Morel, J.E.; Wright, T.P.

    1982-01-01

    Collisionless single particle trajectories are modeled for a single plasma channel having one section curved in a circular arc. The magnetic field is developed by superposition of straight and curved channel segments. The plasma density gives charge and beam-current neutralization. High transport efficiencies are found for turning a relativistic electron beam 90 0 under reasonable conditions of plasma current, beam energy, arc radius, channel radius, and injection distributions in velocity and in position at the channel entrance. Channel exit distributions in velocity and position are found consistent with those for a straight plasma channel of equivalent length. Such transport problems are important in any charged particle-beam application constrained by large diode-to-target distance or by requirements of maximum power deposition in a confined area

  3. Momentum distribution at great depths when electron axial channeling

    International Nuclear Information System (INIS)

    Khokonov, M.Kh.; Tuguz, F.K.

    1989-01-01

    The electron distribution in momenta during axial channeling in thick monocrystals in great depths is estimated. The estimate was carried out with respect to the fact that due to diffusion the angular momentum of the electron can change only in a limited region of phase space and that multiple scattering only takes place on thermal oscillations of nuclei of the crystal lattice. It is shown that in thick monocrystals the distribution in momenta can be considered uniform on the greater part of the way of channeled electrons which can simplity the qualitative consideration of spectral-angular characteristics forming during this radiation

  4. Magnetic Field Generation and Electron Acceleration in Relativistic Laser Channel

    International Nuclear Information System (INIS)

    Kostyukov, I.Yu.; Shvets, G.; Fisch, N.J.; Rax, J.M.

    2001-01-01

    The interaction between energetic electrons and a circularly polarized laser pulse inside an ion channel is studied. Laser radiation can be resonantly absorbed by electrons executing betatron oscillations in the ion channel and absorbing angular momentum from the laser. The absorbed angular momentum manifests itself as a strong axial magnetic field (inverse Faraday effect). The magnitude of this magnetic field is calculated and related to the amount of the absorbed energy. Absorbed energy and generated magnetic field are estimated for the small and large energy gain regimes. Qualitative comparisons with recent experiments are also made

  5. High signal-to-noise ratio sensing with Shack–Hartmann wavefront sensor based on auto gain control of electron multiplying CCD

    International Nuclear Information System (INIS)

    Zhu Zhao-Yi; Li Da-Yu; Hu Li-Fa; Mu Quan-Quan; Yang Cheng-Liang; Cao Zhao-Liang; Xuan Li

    2016-01-01

    High signal-to-noise ratio can be achieved with the electron multiplying charge-coupled-device (EMCCD) applied in the Shack–Hartmann wavefront sensor (S–H WFS) in adaptive optics (AO). However, when the brightness of the target changes in a large scale, the fixed electron multiplying (EM) gain will not be suited to the sensing limitation. Therefore an auto-gain-control method based on the brightness of light-spots array in S–H WFS is proposed in this paper. The control value is the average of the maximum signals of every light spot in an array, which has been demonstrated to be kept stable even under the influence of some noise and turbulence, and sensitive enough to the change of target brightness. A goal value is needed in the control process and it is predetermined based on the characters of EMCCD. Simulations and experiments have demonstrated that this auto-gain-control method is valid and robust, the sensing SNR reaches the maximum for the corresponding signal level, and especially is greatly improved for those dim targets from 6 to 4 magnitude in the visual band. (special topic)

  6. Multi-channel electronically scanned cryogenic pressure sensor

    Science.gov (United States)

    Chapman, John J. (Inventor); Hopson, Purnell, Jr. (Inventor); Kruse, Nancy M. H. (Inventor)

    1995-01-01

    A miniature, multi-channel, electronically scanned pressure measuring device uses electrostatically bonded silicon dies in a multielement array. These dies are bonded at specific sites on a glass, prepatterned substrate. Thermal data is multiplexed and recorded on each individual pressure measuring diaphragm. The device functions in a cryogenic environment without the need of heaters to keep the sensor at constant temperatures.

  7. Relativistic electron planar channeling and diffraction in thin monocrystals

    International Nuclear Information System (INIS)

    Vorob'ev, S.A.; Nurmagambetov, S.B.; Kaplin, V.V.; Rozum, E.I.

    1985-01-01

    The interaction of relativistic electrons with thin monocrystals was investigated in approximation of continuous potential of crystal plane system. Numerical technique for solution of one-dimensional Schroedinger equation with a periodic potential was developed. Numerical solutions conducted according to the technique were used to determine the forms of ngular distributions of electrons located in various zones of lteral motion. Calculation results were applied for analyzing experimentally obtained data on agular distribution of 5.1 MeV electrons projected at small angles onto the (110) planar system of a Si monocrystal. The conducted complex experimental and theoretical: investigations demonstrated the possibility of prevalen occupation of certain states of lateral motion and enabled to determine angular reg in directions of the electron beam projection on a crystal where either channeling effects or those of electron diffraction are important

  8. Electron mobility enhancement in (100) oxygen-inserted silicon channel

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Nuo; King Liu, Tsu-Jae [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States); Takeuchi, Hideki; Hytha, Marek; Cody, Nyles W.; Stephenson, Robert J.; Mears, Robert J. [Mears Technologies, Inc., Wellesley Hills, Massachusetts 02481 (United States); Kwak, Byungil; Cha, Seon Yong [SK Hynix, Icheon-si, Gyeonggi-do 467-701 (Korea, Republic of)

    2015-09-21

    High performance improvement (+88% in peak G{sub m} and >30% in linear and saturation region drain currents) was observed for N-MOSFETs with Oxygen-Inserted (OI) Si channel. From TCAD analysis of the C-V measurement data, the improvement was confirmed to be due to electron mobility enhancement of the OI Si channel (+75% at N{sub inv} = 4.0 × 10{sup 12} cm{sup −2} and +25% at N{sub inv} = 8.0 × 10{sup 12} cm{sup −2}). Raman and high-resolution Rutherford backscattering measurements confirmed that negligible strain is induced in the OI Si layer, and hence, it cannot be used to explain the origin of mobility improvement. Poisson-Schrödinger based quantum mechanical simulation was performed, taking into account phonon, surface roughness and Coulomb scatterings. The OI layer was modeled as a “quasi barrier” region with reference to the Si conduction band edge to confine inversion electrons. Simulation explains the measured electron mobility enhancement as the confinement effect of inversion electrons while the formation of an super-steep retrograde well doping profile in the channel (as a result of dopant diffusion blocking effect accompanied by introduction of the OI layer) also contributes 50%–60% of the mobility improvement.

  9. Formation of a silicon micropore array of a two-dimension electron multiplier by photo electrochemical etching

    International Nuclear Information System (INIS)

    Gao Yanjun; Duanmu Qingduo; Wang Guozheng; Li Ye; Tian Jingquan

    2009-01-01

    A semiconductor PEC etching method is applied to fabricate the n-type silicon deep micropore channel array. In this method, it is important to arrange the direction of the micropore array along the crystal orientation of the Si substrate. Otherwise, serious lateral erosion will happen. The etching process is also relative to the light intensity and HF concentration. 5% HF concentration and 10-15 cm distance between the light source and the silicon wafer are demonstrated to be the best in our experiments. The n-type silicon deep micropore channel array with aperture of 3 μm and aspect ratio of 40-60, whose inner walls are smooth, is finally obtained.

  10. Self-mixing differential vibrometer based on electronic channel subtraction

    International Nuclear Information System (INIS)

    Donati, Silvano; Norgia, Michele; Giuliani, Guido

    2006-01-01

    An instrument for noncontact measurement of differential vibrations is developed, based on the self-mixing interferometer. As no reference arm is available in the self-mixing configuration, the differential mode is obtained by electronic subtraction of signals from two (nominally equal) vibrometer channels, taking advantage that channels are servo stabilized and thus insensitive to speckle and other sources of amplitude fluctuation. We show that electronic subtraction is nearly as effective as field superposition. Common-mode suppression is 25-30 dB, the dynamic range (amplitude) is in excess of 100 μm, and the minimum measurable (differential) amplitude is 20 nm on aB=10 kHz bandwidth. The instrument has been used to measure vibrations of two metal samples kept in contact, revealing the hysteresis cycle in the microslip and gross-slip regimes, which are of interest in the study of friction induced vibration damping of gas turbine blades for aircraft applications

  11. Characterization of encapsulated quantum dots via electron channeling contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Deitz, Julia I.; McComb, David W. [Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Carnevale, Santino D. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); De Graef, Marc [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Grassman, Tyler J., E-mail: grassman.5@osu.edu [Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2016-08-08

    A method for characterization of encapsulated epitaxial quantum dots (QD) in plan-view geometry using electron channeling contrast imaging (ECCI) is presented. The efficacy of the method, which requires minimal sample preparation, is demonstrated with proof-of-concept data from encapsulated (sub-surface) epitaxial InAs QDs within a GaAs matrix. Imaging of the QDs under multiple diffraction conditions is presented, establishing that ECCI can provide effectively identical visualization capabilities as conventional two-beam transmission electron microscopy. This method facilitates rapid, non-destructive characterization of sub-surface QDs giving immediate access to valuable nanostructural information.

  12. Sub-micron resolution selected area electron channeling patterns.

    Science.gov (United States)

    Guyon, J; Mansour, H; Gey, N; Crimp, M A; Chalal, S; Maloufi, N

    2015-02-01

    Collection of selected area channeling patterns (SACPs) on a high resolution FEG-SEM is essential to carry out quantitative electron channeling contrast imaging (ECCI) studies, as it facilitates accurate determination of the crystal plane normal with respect to the incident beam direction and thus allows control the electron channeling conditions. Unfortunately commercial SACP modes developed in the past were limited in spatial resolution and are often no longer offered. In this contribution we present a novel approach for collecting high resolution SACPs (HR-SACPs) developed on a Gemini column. This HR-SACP technique combines the first demonstrated sub-micron spatial resolution with high angular accuracy of about 0.1°, at a convenient working distance of 10mm. This innovative approach integrates the use of aperture alignment coils to rock the beam with a digitally calibrated beam shift procedure to ensure the rocking beam is maintained on a point of interest. Moreover a new methodology to accurately measure SACP spatial resolution is proposed. While column considerations limit the rocking angle to 4°, this range is adequate to index the HR-SACP in conjunction with the pattern simulated from the approximate orientation deduced by EBSD. This new technique facilitates Accurate ECCI (A-ECCI) studies from very fine grained and/or highly strained materials. It offers also new insights for developing HR-SACP modes on new generation high-resolution electron columns. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Charging of insulators by multiply-charged-ion impact probed by slowing down of fast binary-encounter electrons

    Science.gov (United States)

    de Filippo, E.; Lanzanó, G.; Amorini, F.; Cardella, G.; Geraci, E.; Grassi, L.; La Guidara, E.; Lombardo, I.; Politi, G.; Rizzo, F.; Russotto, P.; Volant, C.; Hagmann, S.; Rothard, H.

    2010-12-01

    The interaction of ion beams with insulators leads to charging-up phenomena, which at present are under investigation in connection with guiding phenomena in nanocapillaries with possible application in nanofocused beams. We studied the charging dynamics of insulating foil targets [Mylar, polypropylene (PP)] irradiated with swift ion beams (C, O, Ag, and Xe at 40, 23, 40, and 30 MeV/u, respectively) via the measurement of the slowing down of fast binary-encounter electrons. Also, sandwich targets (Mylar covered with a thin Au layer on both surfaces) and Mylar with Au on only one surface were used. Fast-electron spectra were measured by the time-of-flight method at the superconducting cyclotron of Laboratori Nazionali del Sud (LNS) Catania. The charge buildup leads to target-material-dependent potentials of the order of 6.0 kV for Mylar and 2.8 kV for PP. The sandwich targets, surprisingly, show the same behavior as the insulating targets, whereas a single Au layer on the electron and ion exit side strongly suppresses the charging phenomenon. The accumulated number of projectiles needed for charging up is inversely proportional to electronic energy loss. Thus, the charging up is directly related to emission of secondary electrons.

  14. Charging of insulators by multiply-charged-ion impact probed by slowing down of fast binary-encounter electrons

    International Nuclear Information System (INIS)

    De Filippo, E.; Lanzano, G.; Cardella, G.; Amorini, F.; Geraci, E.; Grassi, L.; Politi, G.; La Guidara, E.; Lombardo, I.; Rizzo, F.; Russotto, P.; Volant, C.; Hagmann, S.; Rothard, H.

    2010-01-01

    The interaction of ion beams with insulators leads to charging-up phenomena, which at present are under investigation in connection with guiding phenomena in nanocapillaries with possible application in nanofocused beams. We studied the charging dynamics of insulating foil targets [Mylar, polypropylene (PP)] irradiated with swift ion beams (C, O, Ag, and Xe at 40, 23, 40, and 30 MeV/u, respectively) via the measurement of the slowing down of fast binary-encounter electrons. Also, sandwich targets (Mylar covered with a thin Au layer on both surfaces) and Mylar with Au on only one surface were used. Fast-electron spectra were measured by the time-of-flight method at the superconducting cyclotron of Laboratori Nazionali del Sud (LNS) Catania. The charge buildup leads to target-material-dependent potentials of the order of 6.0 kV for Mylar and 2.8 kV for PP. The sandwich targets, surprisingly, show the same behavior as the insulating targets, whereas a single Au layer on the electron and ion exit side strongly suppresses the charging phenomenon. The accumulated number of projectiles needed for charging up is inversely proportional to electronic energy loss. Thus, the charging up is directly related to emission of secondary electrons.

  15. Anomalous passage of ultrarelativistic electrons in thick single crystals in axial channeling

    Energy Technology Data Exchange (ETDEWEB)

    Khokonov, M.K. (Moskovskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Yadernoj Fiziki); Telegin, V.I. (Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Atomnoj Ehnergii)

    1983-07-01

    The dynamics of ultrarelativistic axially channeled electrons in thick crystals is studied. It is revealed that a certain fraction of initial electrons have anomalously large dechanneling depths. It is shown also that the dechanneling depth in heavy and light crystals are comparable. In some cases, the number of channeled electrons can strongly increase at the expense of quasi-channeled electrons. The problem of quasi-channeling is also considered.

  16. Operation of gas electron multiplier (GEM) with propane gas at low pressure and comparison with tissue-equivalent gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    De Nardo, L., E-mail: laura.denardo@unipd.it [University of Padova, Physics and Astronomy Department and PD-INFN, via Marzolo 8, I-35131 Padova (Italy); Farahmand, M., E-mail: majid.farahmand@rivm.nl [Centre for Environmental Safety and Security, National Institute for Public Health and the Environment (RIVM), PO Box 1, NL-3720 BA Bilthoven (Netherlands)

    2016-05-21

    A Tissue-Equivalent Proportional Counter (TEPC), based on a single GEM foil of standard geometry, has been tested with pure propane gas at low pressure, in order to simulate a tissue site of about 1 µm equivalent size. In this work, the performance of GEM with propane gas at a pressure of 21 and 28 kPa will be presented. The effective gas gain was measured in various conditions using a {sup 244}Cm alpha source. The dependence of effective gain on the electric field strength along the GEM channel and in the drift and induction region was investigated. A maximum effective gain of about 5×10{sup 3} has been reached. Results obtained in pure propane gas are compared with gas gain measurements in gas mixtures commonly employed in microdosimetry, that is propane and methane based Tissue-Equivalent gas mixtures.

  17. Channeling and coherent bremsstrahlung effects for relativistic positrons and electrons

    International Nuclear Information System (INIS)

    Walker, R.L.

    1976-01-01

    Channeling of positrons in single crystals of silicon was observed in transmission and scattering measurements for incident energies from 16 to 28 MeV. In addition, the spectral dependence upon crystal orientation of the forward coherent bremsstrahlung produced by beams of 28-MeV positrons and electrons incident upon a 5 μm thick single crystal of silicon was measured with a NaI photon spectrometer. Effects of channeling and perhaps of the nonvalidity of the first Born approximation were observed for beam directions near the [111] axis of the crystal, and coherent peaks near 0.5 MeV were observed for a compound interference direction, in agreement with first-order theoretical calculations. 32 fig

  18. Leakage current-induced effects in the silicon microstrip and gas electron multiplier readout chain and their compensation method

    Science.gov (United States)

    Zubrzycka, W.; Kasinski, K.

    2018-04-01

    Leakage current flowing into the charge sensitive amplifier (CSA) is a common issue in many radiation detection systems as it can increase overall system noise, shift a DC baseline or even lead a recording channel to instability. The commonly known leakage current contributor is a detector, however other system components like wires or an input protection circuit may become a serious problem. Compensation of the leakage current resulting from the electrostatic discharge (ESD) protection circuit by properly sizing its components is possible only for a narrow temperature range. Moreover, the leakage current from external sources can be significantly larger. Many applications, especially High Energy Physics (HEP) experiments, require a fast baseline restoration for high input hit rates by applying either a low-value feedback resistor or a high feedback resistance combined with a pulsed reset circuit. Leakage current flowing in the feedback in conjunction with a large feedback resistance supplied with a pulsed reset results in a significant voltage offset between the CSA input and output which can cause problems (e.g. fake hits or instability). This paper shows an issue referred to the leakage current of the ESD protection circuit flowing into the input amplifier. The following analysis and proposed solution is a result of the time and energy readout ASIC project realization for the Compressed Baryonic Matter (CBM) experiment at FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. This chip is purposed to work with microstrip and gaseous detectors, with high average input pulses frequencies (250 kHit/s per channel) and the possibility to process input charge of both polarities. We present measurements of the test structure fabricated in UMC 180 nm technology and propose a solution addressing leakage current related issues. This work combines the leakage current compensation capabilities at the CSA level with high, controllable value of the amplifier

  19. New gas electron-multiplier detectors for the endcap muon system of the CMS experiment at the high-luminosity LHC design and prototype performance

    CERN Document Server

    Gruchala, Marek Michal

    2016-01-01

    The high luminosity LHC will require new detectors in the CMS endcap muon system to suppress the trigger rate of background events, to maintain high trigger efficiency for low transverse momentum muons, to enhance the robustness of muon detection in the high-flux environment of the endcap, and to extend the geometrical acceptance. We report on the design and recent progress towards implementing a new system of large-area, triple-foil gas electron-multiplier (GEM) detectors that will be installed in the first three of five muon detector stations in each endcap, the first station being closest to the interaction point. The first station will extend the geometric acceptance in pseudo-rapidity to eta lt 3.0 from the current limit of eta lt 2.4. The second and third stations will enhance the performance in the range 1.6 lt eta lt 2.4. We describe the design of the chambers and readout electronics and report on the performance of prototype systems in tests with cosmic ray muons, high-energy particlebeams, a...

  20. Channelling and related effects in electron microscopy: The current status

    International Nuclear Information System (INIS)

    Krishnan, K.M.

    1989-05-01

    Channelling or Borrmann effect in electron diffraction has been developed into a versatile, high spatial resolution, crystallographic technique with demonstrated applicability in solving a variety of materials problems. In general, either the characteristic x-ray emissions or the electron energy-loss intensities are monitored as a function of the orientation of the incident beam. The technique, as formulated in the planar geometry has found wide applications in specific site occupancy and valence measurements, determination of small atomic displacements and crystal polarity studies. For site occupancy studies, the appropriate orientations in most cases can be determined by inspection and the analysis carried out according to a simple classification of the crystal structure discussed in this paper. Concentration levels as low as 0.1 wt% can be easily detected. The reciprocity principle may be used to advantage in all these studies, if electron energy-loss spectra are monitored, as both the channelling of the incoming beam and the blocking of the outgoing beam are included in the formulation and analysis. The formulation in the axial geometry is an useful alternative, particularly for monatomic crystals. Localization effects are important if, either the experiment is performed in the axial geometry or if low atomic number elements (z < 11) are detected. In general, the sensitivity to L-shells is lower compared to K-shell excitations. Other experimental parameters to be considered include temperature of the sample, the acceleration voltage and parallelism of the incident beam. Any detrimental effects of channelling on conventional microanalysis can be minimized either by tilting the crystal to an orientation where no lower order diffraction vectors are excited or by using a convergent probe such that a large range of incident beam orientations are averaged in the analysis. 49 refs., 9 figs

  1. Creation and dynamical co-evolution of electron and ion channel transport barriers

    International Nuclear Information System (INIS)

    Newman, D.E.

    2002-01-01

    A wide variety of magnetic confinement devices have found transitions to an enhanced confinement regime. Simple dynamical models have been able to capture much of the dynamics of these barriers however an open question has been the disconnected nature of the electron thermal transport channel sometimes observed in the presence of a standard ('ion channel' barrier. By adding to simple barrier model an evolution equation for electron fluctuations we can investigate the interaction between the formation of the standard ion channel barrier and the somewhat less common electron channel barrier. Barrier formation in the electron channel is even more sensitive to the alignment of the various gradients making up the sheared radial electric field than the ion barrier is. Electron channel heat transport is found to significantly increase after the formation of the ion channel barrier but before the electron channel barrier is formed. This increased transport is important in the barrier evolution. (author)

  2. Vibrationally inelastic electron scattering in a two-channel approximation

    Czech Academy of Sciences Publication Activity Database

    Čársky, Petr; Čurík, Roman

    2008-01-01

    Roč. 41, č. 5 (2008), , , 055203-1-6 ISSN 0953-4075 R&D Projects: GA AV ČR IAA100400501; GA AV ČR 1ET400400413; GA AV ČR KJB400400803; GA ČR GA202/08/0631; GA MŠk ME 857 Institutional research plan: CEZ:AV0Z40400503 Keywords : inelastic electron scattering * two-channel approximation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.089, year: 2008

  3. Soft component of channeled electron radiation in silicon crystals

    International Nuclear Information System (INIS)

    Vnukov, I.E.; Kalinin, B.N.; Kiryakov, A.A.; Naumenko, G.A.; Padalko, D.V.; Potylitsyn, A.P.

    2001-01-01

    Radiation spectrum and orientation dependences of photon yield with the energy much lower than characteristic radiation energy during channeling were measured using a crystal-diffraction spectrometer. For electron drop along axis radiation intensity in the spectral range 30 ≤ ω ≤ 360 keV exceeds by nearly an order the intensity of Bremsstrahlung. The shape of radiation spectrum does not coincide with Bremsstrahlung spectrum. Radiation intensity increases gradually with photons energy growth. Bremsstrahlung spectrum from a disoriented crystalline target is described in a satisfactory manner by the currently used theory with phenomenological account of the medium polarization [ru

  4. Electron transfer from H2 and Ar to stored multiply charged argon ions produced by synchrotron radiation

    International Nuclear Information System (INIS)

    Kravis, S.D.; Church, D.A.; Johnson, B.M.; Meron, M.; Jones, K.W.; Levin, J.C.; Sellin, I.A.; Azuma, Y.; Berrah-Mansour, N.; Berry, H.G.; Druetta, M.

    1992-01-01

    The rate coefficients for electron transfer from Ar and H 2 to Ar q+ ions (3≤q≤6) have been measured using an ion-storage technique in a Penning ion trap. The ions were produced in the trap by K-shell photoionization of Ar atoms, using broadband synchrotron x-ray radiation. K-electron removal resulted in vacancy cascading, yielding a distribution of argon-ion charge states peaked near Ar 4+ . The stored ion gas had an initial temperature near 480 K. The basic data determining the rate coefficients k(Ar q+ ) are the storage time constants of each charge state in the trap, in the presence of a measured pressure of target gas. The results of the measurements (in units of 10 -9 cm 3 s -1 ) are k(Ar 3+ ,H 2 )=4.3(0.7), k(Ar 3+ ,Ar)=1.6(0.2), k(Ar 4+ ,H 2 )=5.2(0.6), k(Ar 4+ ,Ar)=2.5(0.3), k(Ar 5+ ,H 2 )=5.9(0.7), k(Ar 5+ ,Ar)=2.9(0.3), k(Ar 6+ ,H 2 )=8.5(1.2), and k(Ar 6+ ,Ar)=2.5(0.3)

  5. Electron ion interactions in crystal channels: Collisions in ultra-dense electron media

    International Nuclear Information System (INIS)

    Datz, S.; Dittner, P.F.; Gomez del Campo, J.; Krause, H.F.; Rosseel, T.M.; Vane, C.R.

    1990-01-01

    Dielectronic excitation of H-like S, Ca and Ti is shown to occur in the dense electron gas of a crystal channel. Cross sections for collisional ionization of the short lived excited states can then be determined. Ionic excitation can also be achieved by resonant coherent excitation in which case specific m states can be excited for further study. 12 refs., 8 figs

  6. Laser-electron Compton interaction in plasma channels

    International Nuclear Information System (INIS)

    Pogorelsky, I.V.; Ben-Zvi, I.; Hirose, T.

    1998-10-01

    A concept of high intensity femtosecond laser synchrotron source (LSS) is based on Compton backscattering of focused electron and laser beams. The short Rayleigh length of the focused laser beam limits the length of interaction to a few picoseconds. However, the technology of the high repetition rate high-average power picosecond lasers required for high put through LSS applications is not developed yet. Another problem associated with the picosecond laser pulses is undesirable nonlinear effects occurring when the laser photons are concentrated in a short time interval. To avoid the nonlinear Compton scattering, the laser beam has to be split, and the required hard radiation flux is accumulated over a number of consecutive interactions that complicates the LSS design. In order to relieve the technological constraints and achieve a practically feasible high-power laser synchrotron source, the authors propose to confine the laser-electron interaction region in the extended plasma channel. This approach permits to use nanosecond laser pulses instead of the picosecond pulses. That helps to avoid the nonlinear Compton scattering regime and allows to utilize already existing technology of the high-repetition rate TEA CO 2 lasers operating at the atmospheric pressure. They demonstrate the advantages of the channeled LSS approach by the example of the prospective polarized positron source for Japan Linear Collider

  7. Data acquisition and online control system for new gas-electron multiplier detectors in the endcap muon system of the CMS experiment

    CERN Document Server

    Ruiz Alvarez, Jose David

    2016-01-01

    A new data acquisition and on-line control system is being developed for gas-electron multiplier (GEM) detectors which will be installed in the forward region (1.6 \\( < \\eta < \\) 2.2) of the CMS muon spectrometer during the 2nd long shutdown of the LHC, planned for the period 2018-2019. A prototype system employs the TOTEM VFAT2 ASIC that will eventually be replaced with the VFAT3 ASIC, under development. The front-end ASIC communicates over printed circuit lines with an intermediate on-detector board called the opto-hybrid. Data, trigger, and control information is transmitted via optical fiber between the opto-hybrid and an off-detector readout system using micro-TCA technology. On-line software, implemented in the CMS XDAQ framework, includes applications for latency and HV scans, and system management. We report on the operational status of the prototype system that has been tested using cosmic ray muons and extracted high-energy particle beams. This work is preparatory for the operation of a prot...

  8. Resonant influence of a longitudinal hypersonic field on the radiation from channeled electrons

    International Nuclear Information System (INIS)

    Grigoryan, L.Sh.; Mkrtchyan, A.R.; Mkrtchyan, A.H.; Khachatryan, H.F.; Prade, H.; Wagner, W.; Piestrup, M.A.

    2001-01-01

    The wave function of a planar/axially channeled electron with energy 10 MeV≤E<<1 GeV under the influence of a longitudinal hypersonic wave excited in a single crystal is calculated. Conditions for the resonant influence of the hypersonic wave on the quantum state of the channeled electron are deduced. Expressions for the wave function that are applicable in the case of resonance are obtained. Angular and spectral distributions of the radiation intensity from the planar/axially channeled electron are also calculated. The possibility of significant amplification of channeling radiation by a hypersonic wave is substantiated. It is found that the hypersound can excite inverse radiative transitions through which the transversal energy of the channeled electron is increased. These transitions have a resonant nature and can lead to a considerable intensification of the electron channeling radiation. In the case of axial channeling, the resonance radiation is sustained also by direct radiative transitions of the electron

  9. Anomalous passage of ultrarelativistic electrons in thick single crystals in axial channeling

    International Nuclear Information System (INIS)

    Khokonov, M.K.; Telegin, V.I.

    1983-01-01

    The dynamics of ultrarelativistic axially channeled electrons in thick crystals is studied. It is revealed that a certain fraction of initial electrons have anomalously large dechanneling depths. It is shown also that the dechanneling depth in heavy and light crystals are comparable. In some cases, the number of channeled electrons can strongly increase at the expense of quasi-channeled electrons. The problem of quasichanneling is also considered. (author)

  10. A comparison using Faraday cups with 1013 Ω amplifiers and a secondary electron multiplier to measure Os isotopes by negative thermal ionization mass spectrometry.

    Science.gov (United States)

    Wang, Guiqin; Sun, Tiantian; Xu, Jifeng

    2017-10-15

    According to the Johnson-Nyquist noise equation, the value of electron noise is proportional to the square root of the resistor value. This relationship gives a theoretical improvement of 100 in the signal/noise ratio by going from 10 11 Ω to 10 13 Ω amplifiers for Faraday detection in thermal ionization mass spectrometry (TIMS). We measured Os isotopes using static Faraday cups with 10 13 Ω amplifiers in negative thermal ionization mass spectrometry (NTIMS) and compared the results with those obtained with 10 11 Ω amplifiers and by peak-hopping on a single secondary electron multiplier (SEM). We analysed large loads of Os (1 μg) at a range of intensities of 187 OsO 3 (0.02-10 mV) in addition to small loads of Os (5-500 pg) to compare the results of the three methods. Using 10 13 Ω amplifiers, the long-term reproducibility determined from Merck Os was 187 Os/ 188 Os = 0.1211 ± 0.0086 and 0.120229 ± 0.000034 at 0.02 mV and 10 mV of 187 OsO 3 intensities. Meanwhile, the analysed JMC Os loadings of 5 and 500 pg showed 187 Os/ 188 Os = 0.10669 ± 0.00036 and 0.106807 ± 0.000023. In comparison, the values measured by the SEM were 187 Os/ 188 Os = 0.10704 ± 0.00056 and 0.10690 ± 0.00013. All errors are in 2 standard deviation (SD). Both the accuracy and the precision determined using the 10 13 Ω amplifiers and the SEM are identical when the Os amounts are within 10-50 pg. However, the former analysis time can be shortened by approximately two-thirds. The SEM measurement is still the most precise method for Os amounts 50 pg. Copyright © 2017 John Wiley & Sons, Ltd.

  11. Precessed electron beam electron energy loss spectroscopy of graphene: Beyond channelling effects

    Energy Technology Data Exchange (ETDEWEB)

    Yedra, Ll.; Estradé, S., E-mail: sestrade@ub.edu [LENS, MIND-IN2UB, Departament d' Electrònica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); TEM-MAT, CCiT, Universitat de Barcelona, Solé i Sabarís 1, 08028 Barcelona (Spain); Torruella, P.; Eljarrat, A.; Peiró, F. [LENS, MIND-IN2UB, Departament d' Electrònica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Darbal, A. D. [AppFive LLC, 1095 W Rio Salado Pkway, Suite 110, Tempe, Arizona 85281 (United States); Weiss, J. K. [AppFive LLC, 1095 W Rio Salado Pkway, Suite 110, Tempe, Arizona 85281 (United States); NanoMEGAS SPRL, Blvd. Edmond Machtens 79, B-1080 Brussels (Belgium)

    2014-08-04

    The effects of beam precession on the Electron Energy Loss Spectroscopy (EELS) signal of the carbon K edge in a 2 monolayer graphene sheet are studied. In a previous work, we demonstrated the use of precession to compensate for the channeling-induced reduction of EELS signal when in zone axis. In the case of graphene, no enhancement of EELS signal is found in the usual experimental conditions, as graphene is not thick enough to present channeling effects. Interestingly, though it is found that precession makes it possible to increase the collection angle, and, thus, the overall signal, without a loss of signal-to-background ratio.

  12. Calculated characteristics of multichannel photoelectron multipliers

    International Nuclear Information System (INIS)

    Vasil'chenko, V.G.; Dajkovskij, A.G.; Milova, N.V.; Rakhmatov, V.E.; Rykalin, V.I.

    1990-01-01

    Structural features and main calculated characteristics of some modifications of position-sensitive two-coordinate multichannel photoelectron multipliers (PEM) with plate-type multiplying systems are described. The presented PEM structures are free from direct optical and ion feedbacks, provide coordinate resolution ≅ 1 mm with efficiency of photoelectron detection ≅ 90%. Capabilities for using silicon field-effect photocathodes, providing electron extraction into vacuum, as well as prospects of using multichannel multiplying systems for readout of the data from solid detectors are considered

  13. Etched ion tracks in silicon oxide and silicon oxynitride as charge injection or extraction channels for novel electronic structures

    International Nuclear Information System (INIS)

    Fink, D.; Petrov, A.V.; Hoppe, K.; Fahrner, W.R.; Papaleo, R.M.; Berdinsky, A.S.; Chandra, A.; Chemseddine, A.; Zrineh, A.; Biswas, A.; Faupel, F.; Chadderton, L.T.

    2004-01-01

    The impact of swift heavy ions onto silicon oxide and silicon oxynitride on silicon creates etchable tracks in these insulators. After their etching and filling-up with highly resistive matter, these nanometric pores can be used as charge extraction or injection paths towards the conducting channel in the underlying silicon. In this way, a novel family of electronic structures has been realized. The basic characteristics of these 'TEMPOS' (=tunable electronic material with pores in oxide on silicon) structures are summarized. Their functionality is determined by the type of insulator, the etch track diameters and lengths, their areal densities, the type of conducting matter embedded therein, and of course by the underlying semiconductor and the contact geometry. Depending on the TEMPOS preparation recipe and working point, the structures may resemble gatable resistors, condensors, diodes, transistors, photocells, or sensors, and they are therefore rather universally applicable in electronics. TEMPOS structures are often sensitive to temperature, light, humidity and organic gases. Also light-emitting TEMPOS structures have been produced. About 37 TEMPOS-based circuits such as thermosensors, photosensors, humidity and alcohol sensors, amplifiers, frequency multipliers, amplitude modulators, oscillators, flip-flops and many others have already been designed and successfully tested. Sometimes TEMPOS-based circuits are more compact than conventional electronics

  14. Ionic fragmentation channels in electron collisions of small molecular ions

    International Nuclear Information System (INIS)

    Hoffmann, Jens

    2009-01-01

    Dissociative Recombination (DR) is one of the most important loss processes of molecular ions in the interstellar medium (IM). Ion storage rings allow to investigate these processes under realistic conditions. At the Heidelberg test storage ring TSR a new detector system was installed within the present work in order to study the DR sub-process of ion pair formation (IPF). The new detector expands the existing electron target setup by the possibility to measure strongly deflected negative ionic fragments. At the TSR such measurements can be performed with a uniquely high energy resolution by independently merging two electron beams with the ion beam. In this work IPF of HD + , H 3 + and HF + has been studied. In the case of HD + the result of the high resolution experiment shows quantum interferences. Analysis of the quantum oscillations leads to a new understanding of the reaction dynamics. For H 3 + it was for the first time possible to distinguish different IPF channels and to detect quantum interferences in the data. Finally the IPF of HF + was investigated in an energy range, where in previous experiments no conclusive results could be obtained. (orig.)

  15. Electron multiplier for the measurement of an ion current on a mass spectrometer; Multiplicateur d'electrons pour la mesure de courant d'ions sur un spectrometre de masse

    Energy Technology Data Exchange (ETDEWEB)

    Lohez, P; Nief, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1957-07-01

    The apparatus described is designed to measure weak ion currents received at the collector of a mass spectrometer. The report describes successively the study of electron paths in the multiplier by the method of analogy, using rubber membranes, and the practical details of construction of the apparatus. The variation with surface treatment of the secondary emission coefficient of the alloy CuBe containing 2 per cent Be, which makes up the dynodes, and the influence of the voltage on the gain per stage, are discussed. Results of tests regarding: the influence of the ion mass on the gain, the background of the instrument and the energy distribution of the impulses coming out on a high gain multiplier (q.q. 10{sup 7}) are given. Finally the performances of the multiplier are reported. 1- For a low gain (10{sup 4}), precision and reproducibility comparable to the electrometer valve, sensitivity 100 times greater, currents capable of detection 10{sup -17} Ampere. 2- For a high gain (10{sup 7}) and measurement by impulse counting, currents capable of detection 10{sup -19} Ampere. Mounting difficult to use on a mass spectrometer. (author) [French] L'appareil decrit est destine a la mesure des faibles courants d'ions re s au collecteur d'un spectrometre de masse. Le rapport decrit successivement l'etude des trajectoires des electrons dans le multiplicateur, par la methode analogique de la menbrane en caoutchouc, et la realisation pratique de l'appareil. La variation du coefficient d'emission secondaire de l'alliage CuBe a 2 pour cent de Be, constituant les dynodes suivant le traitement des surfaces, et l'influence de la tension sur le gain par etage sont discutees. Des resultats d'essais concernant: l'influence de la masse des ions sur le gain, le bruit de fond de l'appareil et la repartition en energie des impulsions de sortie sur un multiplicateur a gain eleve (q.q. 10{sup 7}) sont donnes. Enfin, sont rapportees les performances du multiplicateur. 1- pour un gain faible

  16. Phenomenological studies of electron-beam transport in wire-plasma channels

    International Nuclear Information System (INIS)

    Lockwood, G.J.; Beezhold, W.

    1980-01-01

    Multiple electron-beam transport in air through plasma channels is an important method for delivering many intense beams to a bremsstrahlung converter system. This paper reports work intended to optimize this transport technique with emphasis on transport through curved channels and on transport efficiencies. Curved-channel transport allows accelerators such as Sandia's PROTO II and PBFA I facilities to be used as flash x-ray sources for weapon effects simulation without reconfiguring the diodes or developing advanced converters. The formation mechanisms of wire-initiated plasma channels in air were examined and the subsequent transport efficiencies of relativistic electron beams through various-length straight and curved plasma channels were determined. Electron transport efficiency through a channel was measured to be 80 to 100% of a zero length channel for 40 cm long straight channels and for curved channels which re-directed the electron beam through an angle of 90 0 . Studies of simultaneous e-beam transport along two curved channels closely spaced at the converter showed that transport efficiency remained at 80 to 100%. However, it was observed that the two e-beams were displaced towards each other. Transport efficiency was observed to depend only weakly on parameters such as wire material, wire length and shape, diode anode aperture, e-beam injection time, and wire-channel applied voltage. For off-center injection conditions the electron beam strongly perturbed the plasma channel in periodic or regularly spaced patterns even though the total energy lost by the electron beam remained small. Plasma-channel transport, when all experimental parameters have been optimized for maximum transport efficiency, is a workable method for directing electron beams to a converter target

  17. The Multiply Handicapped Child.

    Science.gov (United States)

    Wolf, James M., Ed.; Anderson, Robert M., Ed.

    Articles presented in the area of the medical and educational challenge of the multiply handicapped child are an overview of the problem, the increasing challenge, congenital malformations, children whose mothers had rubella, prematurity and deafness, the epidemiology of reproductive casualty, and new education for old problems. Discussions of…

  18. The Multiplier Effect.

    Science.gov (United States)

    Flowers, William L., Jr.; Harris, John B.

    1981-01-01

    The multiplier effect is discussed as it applies to the field of continuing education. The authors' main point is that one grant or contract can, and should, be used as the basis for building organizational competencies and capabilities that will secure other funds. (Author/CT)

  19. Mean secondary electron yield of avalanche electrons in the channels of a microchannel plate detector

    International Nuclear Information System (INIS)

    Funsten, H.O.; Suszcynsky, D.M.; Harper, R.W.

    1996-01-01

    By modeling the statistical evolution of an avalanche created by 20 keV protons impacting the input surface of a z-stack microchannel plate (MCP) detector, the mean secondary electron yield γ C of avalanche electrons propagating through a MCP channel is measured to equal 1.37 for 760 V per MCP in the z stack. This value agrees with other studies that used MCP gain measurements to infer γ C . The technique described here to measure γ C is independent of gain saturation effects and simplifying assumptions used in the segmented dynode model, both of which can introduce errors when inferring γ C through gain measurements. copyright 1996 American Institute of Physics

  20. Investigation of quantum states of fast electrons under planar channeling in silicon crystals

    International Nuclear Information System (INIS)

    Gridnev, V.I.; Kaplin, V.V.; Khlabutin, V.G.; Rozum, E.I.; Vorobiev, S.A.

    1987-01-01

    The angular distributions of (1.87 to 5.7) MeV electrons channeled in 2 μm Si crystals along (100), (110), and (111) atomic planes are measured. The half-width of measured angular distributions is defined by a critical Lindhard angle. A relation is obtained connecting those energies of electrons at which their angular distributions are similar for various atomic planes. The effect of a 'critical energy' under planar channeling of electrons is found and investigated. (author)

  1. Total yield of channeling radiation from relativistic electrons in thin Si and W crystals

    International Nuclear Information System (INIS)

    Abdrashitov, S.V.; Bogdanov, O.V.; Dabagov, S.B.; Pivovarov, Yu.L.; Tukhfatullin, T.A.

    2013-01-01

    Orientation dependences of channeling radiation total yield from relativistic 155–855 MeV electrons at both 〈1 0 0〉 axial and (1 0 0) planar channeling in thin silicon and tungsten crystals are studied by means of computer simulations. The model as well as computer code developed allows getting the quantitative results for orientation dependence of channeling radiation that can be used for crystal alignment in channeling experiments and/or for diagnostics of initial angular divergence of electron beam

  2. Microwave Frequency Multiplier

    Science.gov (United States)

    Velazco, J. E.

    2017-02-01

    High-power microwave radiation is used in the Deep Space Network (DSN) and Goldstone Solar System Radar (GSSR) for uplink communications with spacecraft and for monitoring asteroids and space debris, respectively. Intense X-band (7.1 to 8.6 GHz) microwave signals are produced for these applications via klystron and traveling-wave microwave vacuum tubes. In order to achieve higher data rate communications with spacecraft, the DSN is planning to gradually furnish several of its deep space stations with uplink systems that employ Ka-band (34-GHz) radiation. Also, the next generation of planetary radar, such as Ka-Band Objects Observation and Monitoring (KaBOOM), is considering frequencies in the Ka-band range (34 to 36 GHz) in order to achieve higher target resolution. Current commercial Ka-band sources are limited to power levels that range from hundreds of watts up to a kilowatt and, at the high-power end, tend to suffer from poor reliability. In either case, there is a clear need for stable Ka-band sources that can produce kilowatts of power with high reliability. In this article, we present a new concept for high-power, high-frequency generation (including Ka-band) that we refer to as the microwave frequency multiplier (MFM). The MFM is a two-cavity vacuum tube concept where low-frequency (2 to 8 GHz) power is fed into the input cavity to modulate and accelerate an electron beam. In the second cavity, the modulated electron beam excites and amplifies high-power microwaves at a frequency that is a multiple integer of the input cavity's frequency. Frequency multiplication factors in the 4 to 10 range are being considered for the current application, although higher multiplication factors are feasible. This novel beam-wave interaction allows the MFM to produce high-power, high-frequency radiation with high efficiency. A key feature of the MFM is that it uses significantly larger cavities than its klystron counterparts, thus greatly reducing power density and arcing

  3. Fiscal Multipliers in Ukraine

    OpenAIRE

    Pritha Mitra; Tigran Poghosyan

    2015-01-01

    Amid renewed crisis, falling tax revenues, and rising debt, Ukraine faces serious fiscal consolidation needs. Durable fiscal adjustment can support economic confidence and rebuild buffers but what is its overall impact on growth? How effective are revenue versus spending instruments? Does current or capital spending have a larger impact? Applying a structural vector autoregressive model, this paper finds that Ukraine’s near-term revenue and spending multipliers are well below one. In the medi...

  4. Why Multiply by "g"?

    Science.gov (United States)

    Nelson, Jane Bray

    2012-01-01

    As a new physics teacher, I was explaining how to find the weight of an object sitting on a table near the surface of the Earth. It bothered me when a student asked, "The object is not accelerating so why do you multiply the mass of the object by the acceleration due to gravity?" I answered something like, "That's true, but if the table were not…

  5. Coincident detection of electrons ejected at large angles and target recoil ions produced in multiply ionizing collisions for the 1-MeV/u Oq++Ar collision system

    International Nuclear Information System (INIS)

    Gaither III, C.C.; Breinig, M.; Berryman, J.W.; Hasson, B.F.; Richards, J.D.; Price, K.

    1993-01-01

    The angular distributions of energetic electrons ejected at angles between 45 degree and 135 degree with respect to the incident-beam direction have been measured in coincidence with the charge states of the target recoil ions produced in multiply ionizing collisions for the 1-MeV/u O q+ (q=4,7)+Ar collision systems. These measurements have been made for ∼179-, ∼345-, and ∼505-eV electrons. Additionally, the energy distributions of electrons ejected into specific angular regions have been measured. Ar LMM satellite Auger electrons appear as a peak in the energy spectrum of electrons ejected at all large angles. The center of this peak is found at an electron energy of ∼179 eV. Electrons with ∼179 eV energy, ejected at large angles, are preferentially produced in coincidence with recoil ions of charge state 4+. Electrons with ∼345 eV energy and ∼505 eV energy ejected at large angles are preferentially produced in coincidence with recoil ions of charge state 3+. The angular distributions for these electrons are strongly peaked in the forward direction; essentially no electrons are observed at angles larger than 90 degree. These results are consistent with the dominant production mechanism for energetic electrons ejected at large angles being a binary-encounter process. Differential cross sections have been calculated from these angular distributions. They are on the order of 10 -21 cm 2 /(eV sr)

  6. Angular distributions of relativistic electrons under channeling in half-wavelength crystal and corresponding radiation

    International Nuclear Information System (INIS)

    Takabayashi, Y.; Bagrov, V.G.; Bogdanov, O.V.; Pivovarov, Yu.L.; Tukhfatullin, T.A.

    2015-01-01

    New experiments on channeling of 255 MeV electrons in a half-wavelength crystals (HWC) were performed at SAGA Light Source facilities. The simulations of trajectories for (2 2 0) and (1 1 1) planar channeling in Si were performed using the computer code BCM-1.0. Comparison of experimental and theoretical results shows a good agreement. The results of calculations of spectral distribution of radiation in forward direction (θ = 0°) from 255 MeV electrons at (2 2 0) channeling in HWC silicon are presented. Qualitative comparison with radiation spectrum from an electron moving in an arc is performed

  7. Encoding Schemes For A Digital Optical Multiplier Using The Modified Signed-Digit Number Representation

    Science.gov (United States)

    Lasher, Mark E.; Henderson, Thomas B.; Drake, Barry L.; Bocker, Richard P.

    1986-09-01

    The modified signed-digit (MSD) number representation offers full parallel, carry-free addition. A MSD adder has been described by the authors. This paper describes how the adder can be used in a tree structure to implement an optical multiply algorithm. Three different optical schemes, involving position, polarization, and intensity encoding, are proposed for realizing the trinary logic system. When configured in the generic multiplier architecture, these schemes yield the combinatorial logic necessary to carry out the multiplication algorithm. The optical systems are essentially three dimensional arrangements composed of modular units. Of course, this modularity is important for design considerations, while the parallelism and noninterfering communication channels of optical systems are important from the standpoint of reduced complexity. The authors have also designed electronic hardware to demonstrate and model the combinatorial logic required to carry out the algorithm. The electronic and proposed optical systems will be compared in terms of complexity and speed.

  8. Two-Channel Kondo Effect in a Modified Single Electron Transistor

    Science.gov (United States)

    Oreg, Yuval; Goldhaber-Gordon, David

    2003-04-01

    We suggest a simple system of two electron droplets which should display two-channel Kondo behavior at experimentally accessible temperatures. Stabilization of the two-channel Kondo fixed point requires fine control of the electrochemical potential in each droplet, which can be achieved by adjusting voltages on nearby gate electrodes. We study the conditions for obtaining this type of two-channel Kondo behavior, discuss the experimentally observable consequences, and explore the gener­alization to the multichannel Kondo case.

  9. Investigation of betatron instability in a wiggler pumped ion-channel free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Raghavi, A [Physics Department, Payame Noor University, 19395-4697 (Iran, Islamic Republic of); Mehdian, H, E-mail: Raghavi@tmu.ac.ir, E-mail: Mehdian@tmu.ac.ir [Department of Physics, Teacher Training University, Tehran (Iran, Islamic Republic of)

    2011-10-15

    Betatron emission from an ion-channel free electron laser in the presence of a helical wiggler pump and in the high gain regime is studied. The dispersion relation and the frequency of betatron emission are derived. Growth rate is illustrated and maximum growth rate as a function of ion-channel density is considered. Finally, the relation between beam energy, the density of ion channel and the region of betatron emission is discussed.

  10. Quantum ballistic transport by interacting two-electron states in quasi-one-dimensional channels

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Danhong [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Gumbs, Godfrey [Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Abranyos, Yonatan [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Pepper, Michael; Kumar, Sanjeev [Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE (United Kingdom); London Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0AH (United Kingdom)

    2015-11-15

    For quantum ballistic transport of electrons through a short conduction channel, the role of Coulomb interaction may significantly modify the energy levels of two-electron states at low temperatures as the channel becomes wide. In this regime, the Coulomb effect on the two-electron states is calculated and found to lead to four split energy levels, including two anticrossing-level and two crossing-level states. Moreover, due to the interplay of anticrossing and crossing effects, our calculations reveal that the ground two-electron state will switch from one anticrossing state (strong confinement) to a crossing state (intermediate confinement) as the channel width gradually increases and then back to the original anticrossing state (weak confinement) as the channel width becomes larger than a threshold value. This switching behavior leaves a footprint in the ballistic conductance as well as in the diffusion thermoelectric power of electrons. Such a switching is related to the triple spin degeneracy as well as to the Coulomb repulsion in the central region of the channel, which separates two electrons away and pushes them to different channel edges. The conductance reoccurrence region expands from the weak to the intermediate confinement regime with increasing electron density.

  11. Spectral distribution of radiation on plane and axial channeling of ultrarelativistic electrons

    International Nuclear Information System (INIS)

    Bazylev, V.A.; Glebov, V.I.; Zhevago, N.K.

    1980-01-01

    The spectral angular and polarization charactristics of the radiation from channeled ultrarelativistic electrons are calculated. Analytic expressions for the spectral-angular power density of the radiation are obtained for some realistic models of the continuous potential of the crystal planes and axes. A critical analysis is also presented of some existent results of the theory of radiation on channeling

  12. Anomaly in the Kumakhov radiation temperature dependence at axial channeling of electrons

    Energy Technology Data Exchange (ETDEWEB)

    Komarov, F.F.; Telegin, V.I.; Khokonov, M.Kh.

    1983-01-01

    The results of numerical solution of a kinetic equation for distribution function of axially channelled electrons obtained by Belostritsky and Kumakhov at different temperatures of crystals and calculated for the determined electron distributions spectral density of radiation are given. Analysis of the obtained dependence of the number of channelled 5 GeV electrons in tungsten along the <111> axis on depth Z has revealed that 2% of incidence beam electrons have anomalously large depths of dechannelling. Ratio of electrons with large by modulus cross section energies grows at decreasing crystal temperature from 293 to 40 K and, therefore, radiation intensity increases. Two-fold increase of radiation intensity can be attained at axial channelling of 1 GeV electrons in tungsten <111> at the temperatures of the crystal equal to 40 and 293 K and its thickness equal to 220 ..mu..m.

  13. Optical studies of multiply excited states

    International Nuclear Information System (INIS)

    Mannervik, S.

    1989-01-01

    Optical studies of multiply-excited states are reviewed with emphasis on emission spectroscopy. From optical measurements, properties such as excitation energies, lifetimes and autoionization widths can be determined with high accuracy, which constitutes a challenge for modern computational methods. This article mainly covers work on two-, three- and four-electron systems, but also sodium-like quartet systems. Furthermore, some comments are given on bound multiply-excited states in negative ions. Fine structure effects on transition wavelengths and lifetimes (autoionization) are discussed. In particular, the most recent experimental and theoretical studies of multiply-excited states are covered. Some remaining problems, which require further attention, are discussed in more detail. (orig.) With 228 refs

  14. Channeling effect in electronic spectra produced by grazing impact of fast protons on insulator surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Archubi, C D; Gravielle, M S, E-mail: archubi@iafe.uba.a, E-mail: msilvia@iafe.uba.a [Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67, Sucursal 28, 1428, Buenos Aires (Argentina)

    2009-11-01

    Electron emission due to grazing scattering of fast protons from LiF and KCl surfaces is studied under axial incidence conditions. The differential emission probability is calculated within a distorted-wave formalism, taking into account axial channeled trajectories. For different emission angles, electronic spectra for proton incidence along the two principal crystal axes ([100] and [110]) are compared with those corresponding to an impact velocity in a random direction, finding effects associated with the channeling conditions.

  15. Solution of the Fokker-Planck equation for axially-channeled relativistic electrons

    International Nuclear Information System (INIS)

    Muralev, V.A.; Telegin, V.I.

    1981-01-01

    A method of the two dimensional kinetic equation of the Fokker-Planck type for axially-channeled electrons is proposed. This equation has been obtained recently by Beloshitsky and Kumakhov to describe the diffusion of channeling negative particles over the transverse energy and angular momentum. The results of computation of the dechanneling function of 1 GeV electrons in tungsten are presented. (author)

  16. A radiation-hard dual-channel 12-bit 40 MS/s ADC prototype for the ATLAS liquid argon calorimeter readout electronics upgrade at the CERN LHC

    Energy Technology Data Exchange (ETDEWEB)

    Kuppambatti, J. [Columbia University, Dept. of Electrical Engineering, New York, NY (United States); Ban, J. [Columbia University, Nevis Laboratories, Irvington, NY (United States); Andeen, T., E-mail: tandeen@utexas.edu [Columbia University, Nevis Laboratories, Irvington, NY (United States); Brown, R.; Carbone, R. [Columbia University, Nevis Laboratories, Irvington, NY (United States); Kinget, P. [Columbia University, Dept. of Electrical Engineering, New York, NY (United States); Brooijmans, G.; Sippach, W. [Columbia University, Nevis Laboratories, Irvington, NY (United States)

    2017-05-21

    The readout electronics upgrade for the ATLAS Liquid Argon Calorimeters at the CERN Large Hadron Collider requires a radiation-hard ADC. The design of a radiation-hard dual-channel 12-bit 40 MS/s pipeline ADC for this use is presented. The design consists of two pipeline A/D channels each with four Multiplying Digital-to-Analog Converters followed by 8-bit Successive-Approximation-Register analog-to-digital converters. The custom design, fabricated in a commercial 130 nm CMOS process, shows a performance of 67.9 dB SNDR at 10 MHz for a single channel at 40 MS/s, with a latency of 87.5 ns (to first bit read out), while its total power consumption is 50 mW/channel. The chip uses two power supply voltages: 1.2 and 2.5 V. The sensitivity to single event effects during irradiation is measured and determined to meet the system requirements.

  17. Radiation from 39 and 45 MEV electrons channeled in lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Diedrich, E.; Kufner, W.; Buschhorn, G. (Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (Germany). Werner-Heisenberg-Inst. fuer Physik)

    1991-12-01

    Channeling radiation from 39 and 45 MeV electrons channeled along the (0001) axis, the (0110) plane and the (1210) plane of a 30 {mu}m thick LiNbO{sub 3} crystal has been measured. Calculations of the planar crystal potentials were performed by means of the many-beam formalism. Good agreement between theory and experiment is obtained for the planar channeling radiation. Associated with channeling, additional radiation lines have been observed, which may be explained by a periodic perturbation of the continuum potential. (author).

  18. Radiation from planar channeled 5-55 GeV/c positrons and electrons

    International Nuclear Information System (INIS)

    Atkinson, M.; Sharp, P.H.; Giddings, D.; Bussey, P.J.

    1982-01-01

    The emission of radiation from 5 to 55 GeV/c planar channeled positrons and electrons passing through a 135 μ thick silicon-crystal has been investigated. The intensity of the channeling-radiation is found to be 10 to 30 times the intensity of normal bremsstrahlung. For channeled electrons no structure is found in the spectrum, whereas strong and sharp peaks are found for positrons. This peak structure is extremely sharp at 5 GeV/c and for momenta above 20 GeV/c the structure disappears. For a classical description of channeling, but using an anharmonic potential, certain energies are found for which the maximum energy of the channeling radiation is practically independent of transverse energy. The possibility of making a monoenergetic γ-source in the range of 10-100 MeV is mentioned. (orig.)

  19. The effect of closed channels on the electron impact excitation of Mg +, Cd + ions

    Science.gov (United States)

    Li, Yueming

    2018-04-01

    Based on the developed method for solving the multi-channel equation, which had been applied to the calculations of several kinds of ions including only open-open interactions, closed channels and their interactions with open channels have been studied. The wave functions of the closed channels are also expressed in terms of their homogeneous solutions which is just the same as for open channels. The homogeneous solutions are described and solved in WKB form, therefore the regular and irregular solutions as well as the quantum defect numbers can be obtained simultaneously. Excitations of Mg +, Cd + ions impact by electrons are calculated for energies close to the thresholds. The results are compared with those of the experimental observations and previous theoretical calculations. The effect of including the closed channels, especially when the energy passes through the resonance energies, has been discussed according to the deduced formulae and the calculated results.

  20. Electron-impact excitation of multiply-charged ions using energy loss in merged beams: e + Si3+(3s2S1/2) → e + Si3+(3p2P1/2,3/2)

    International Nuclear Information System (INIS)

    Wahlin, E.K.; Thompson, J.S.; Dunn, G.H.; Phaneuf, R.A.; Gregory, D.C.; Smith, A.C.H.

    1990-01-01

    For the first time absolute total cross sections for electron-impact excitation of a multiply-charged ion have been measured using an electron-energy-loss technique. Measurements were made near threshold for the process e + Si 3+ (3s 2 S 1/2 ) → e + Si 3+ (3p 2 P 1/2 , 3/2 ) -- 8.88 eV. The 10 -15 cm 2 measured cross section agrees with results of 7-state close coupling calculations to better than the ±20% (90% CL) total uncertainty of the measurements. Convoluting the theoretical curve with a Gaussian energy distribution indicates an energy width of 0.15 approx-lt ΔE approx-lt 0.20 eV. 12 refs., 2 figs

  1. X-ray and γ-ray emission from channeled relativistic electrons and positrons

    International Nuclear Information System (INIS)

    Terhune, R.W.; Pantell, R.H.

    1977-01-01

    The characteristics of the radiation from channeled relativistic electrons and positrons are discussed and model calculations carried out. Radiation near 2.5 keV associated with transitions etween the 2 p→1s eigenstates of 2-MeV electrons channeled along the axis of MgO is predicted with 50 times the usual bremsstrahlung intensity in a 10% bandwidth. Recent low-energy bremsstrahlung measurements made with 28-MeV electrons propagating along an axis in silicon are interpreted in terms of this model

  2. Site-specific electronic structure analysis by channeling EELS and first-principles calculations.

    Science.gov (United States)

    Tatsumi, Kazuyoshi; Muto, Shunsuke; Yamamoto, Yu; Ikeno, Hirokazu; Yoshioka, Satoru; Tanaka, Isao

    2006-01-01

    Site-specific electronic structures were investigated by electron energy loss spectroscopy (EELS) under electron channeling conditions. The Al-K and Mn-L(2,3) electron energy loss near-edge structure (ELNES) of, respectively, NiAl2O4 and Mn3O4 were measured. Deconvolution of the raw spectra with the instrumental resolution function restored the blunt and hidden fine features, which allowed us to interpret the experimental spectral features by comparing with theoretical spectra obtained by first-principles calculations. The present method successfully revealed the electronic structures specific to the differently coordinated cationic sites.

  3. Planar channeled relativistic electrons and positrons in the field of resonant hypersonic wave

    International Nuclear Information System (INIS)

    Grigoryan, L.Sh.; Mkrtchyan, A.H.; Khachatryan, H.F.; Tonoyan, V.U.; Wagner, W.

    2003-01-01

    The wave function of a planar channeled relativistic particle (electron, positron) in a single crystal excited by longitudinal hypersonic vibrations (HVs) is determined. The obtained expression is valid for periodic (not necessarily harmonic) HV of desired profile and single crystals with an arbitrary periodic continuous potential. A revised formula for the wave number of HV that exert resonance influence on the state of a channeled particle was deduced to allow for non-linear effects due to the influence of HV

  4. FILTRES: a 128 channels VLSI mixed front-end readout electronic development for microstrip detectors

    International Nuclear Information System (INIS)

    Anstotz, F.; Hu, Y.; Michel, J.; Sohler, J.L.; Lachartre, D.

    1998-01-01

    We present a VLSI digital-analog readout electronic chain for silicon microstrip detectors. The characteristics of this circuit have been optimized for the high resolution tracker of the CERN CMS experiment. This chip consists of 128 channels at 50 μm pitch. Each channel is composed by a charge amplifier, a CR-RC shaper, an analog memory, an analog processor, an output FIFO read out serially by a multiplexer. This chip has been processed in the radiation hard technology DMILL. This paper describes the architecture of the circuit and presents test results of the 128 channel full chain chip. (orig.)

  5. UWB delay and multiply receiver

    Energy Technology Data Exchange (ETDEWEB)

    Dallum, Gregory E.; Pratt, Garth C.; Haugen, Peter C.; Romero, Carlos E.

    2013-09-10

    An ultra-wideband (UWB) delay and multiply receiver is formed of a receive antenna; a variable gain attenuator connected to the receive antenna; a signal splitter connected to the variable gain attenuator; a multiplier having one input connected to an undelayed signal from the signal splitter and another input connected to a delayed signal from the signal splitter, the delay between the splitter signals being equal to the spacing between pulses from a transmitter whose pulses are being received by the receive antenna; a peak detection circuit connected to the output of the multiplier and connected to the variable gain attenuator to control the variable gain attenuator to maintain a constant amplitude output from the multiplier; and a digital output circuit connected to the output of the multiplier.

  6. Accurate electron channeling contrast analysis of a low angle sub-grain boundary

    International Nuclear Information System (INIS)

    Mansour, H.; Crimp, M.A.; Gey, N.; Maloufi, N.

    2015-01-01

    High resolution selected area channeling pattern (HR-SACP) assisted accurate electron channeling contrast imaging (A-ECCI) was used to unambiguously characterize the structure of a low angle grain boundary in an interstitial-free-steel. The boundary dislocations were characterized using TEM-style contrast analysis. The boundary was determined to be tilt in nature with a misorientation angle of 0.13° consistent with the HR-SACP measurements. The results were verified using high accuracy electron backscatter diffraction (EBSD), confirming the approach as a discriminating tool for assessing low angle boundaries

  7. Channeling of electrons in a crossed laser field

    Directory of Open Access Journals (Sweden)

    S. B. Dabagov

    2015-06-01

    Full Text Available In this article a new analytical description of the effective interaction potential for a charged particle with the field of two interfering laser beams is presented. The potential dependence on the lasers intensities, orientation and parameters of the particle entering the considered system is analyzed. For the first time the phenomenon of effective potential inversion (or “relativistic reversal” is described for arbitrary lasers crossing angle. Threshold electron velocity values for the phenomenon are introduced and its extended illustration based on numerical simulations for two laser beams polarizations is presented. In addition the projectile radiation spectral distribution is given and general estimations on the expected beam radiation yield are outlined.

  8. Cyanated diazatetracene diimides with ultrahigh electron affinity for n-channel field effect transistors

    KAUST Repository

    Ye, Qun

    2013-03-15

    Several diazatetracene diimides with high electron affinity (up to 4.66 eV!) were prepared and well characterized. The LUMO energy level of these electron-deficient molecules was found to be closely related to their material stability. Compound 7 with ultrahigh electron affinity suffered from reduction and hydrolysis in the presence of silica gel or water. The stable compounds 3 and 6 showed n-channel FET behavior with an average electron mobility of 0.002 and 0.005 cm2 V-1 s-1, respectively, using a solution processing method. © 2013 American Chemical Society.

  9. GeV electron beams from centimeter-scale channel guided laser wakefield

    International Nuclear Information System (INIS)

    Gonsalves, A.; Nakamura, K.; Panasenko, D.; Toth, Cs.; Esarey, E.; Schroeder; Hooker, S.M.; Leemans, W.P.; Hooker, S.M.

    2007-01-01

    Results are presented on the generation of quasi-monoenergetic electron beams with energy up to 1 GeV using a 40TW laser and a 3.3 cm-long hydrogen-filled capillary discharge waveguide. Electron beams were not observed without a plasma channel, indicating that self-focusing alone could not be relied upon for effective guiding of the laser pulse. Results are presented of the electron beam spectra, and the dependence of the reliability of producing electron beams as a function of laser and plasma parameters

  10. Laser-driven relativistic electron dynamics in a cylindrical plasma channel

    Science.gov (United States)

    Geng, Pan-Fei; Lv, Wen-Juan; Li, Xiao-Liang; Tang, Rong-An; Xue, Ju-Kui

    2018-03-01

    The energy and trajectory of the electron, which is irradiated by a high-power laser pulse in a cylindrical plasma channel with a uniform positive charge and a uniform negative current, have been analyzed in terms of a single-electron model of direct laser acceleration. We find that the energy and trajectory of the electron strongly depend on the positive charge density, the negative current density, and the intensity of the laser pulse. The electron can be accelerated significantly only when the positive charge density, the negative current density, and the intensity of the laser pulse are in suitable ranges due to the dephasing rate between the wave and electron motion. Particularly, when their values satisfy a critical condition, the electron can stay in phase with the laser and gain the largest energy from the laser. With the enhancement of the electron energy, strong modulations of the relativistic factor cause a considerable enhancement of the electron transverse oscillations across the channel, which makes the electron trajectory become essentially three-dimensional, even if it is flat at the early stage of the acceleration. Project supported by the National Natural Science Foundation of China (Grant Nos. 11475027, 11765017, 11764039, 11305132, and 11274255), the Natural Science Foundation of Gansu Province, China (Grant No. 17JR5RA076), and the Scientific Research Project of Gansu Higher Education, China (Grant No. 2016A-005).

  11. Never at rest: insights into the conformational dynamics of ion channels from cryo-electron microscopy.

    Science.gov (United States)

    Lau, Carus; Hunter, Mark J; Stewart, Alastair; Perozo, Eduardo; Vandenberg, Jamie I

    2018-04-01

    The tightly regulated opening and closure of ion channels underlies the electrical signals that are vital for a wide range of physiological processes. Two decades ago the first atomic level view of ion channel structures led to a detailed understanding of ion selectivity and conduction. In recent years, spectacular developments in the field of cryo-electron microscopy have resulted in cryo-EM superseding crystallography as the technique of choice for determining near-atomic resolution structures of ion channels. Here, we will review the recent developments in cryo-EM and its specific application to the study of ion channel gating. We will highlight the advantages and disadvantages of the current technology and where the field is likely to head in the next few years. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

  12. Field-reversed bubble in deep plasma channels for high quality electron acceleration

    CERN Document Server

    Pukhov, A; Tueckmantel, T; Thomas, J; Yu, I; Kostyukov, Yu

    2014-01-01

    We study hollow plasma channels with smooth boundaries for laser-driven electron acceleration in the bubble regime. Contrary to the uniform plasma case, the laser forms no optical shock and no etching at the front. This increases the effective bubble phase velocity and energy gain. The longitudinal field has a plateau that allows for mono-energetic acceleration. We observe as low as 10−3 r.m.s. relative witness beam energy uncertainty in each cross-section and 0.3% total energy spread. By varying plasma density profile inside a deep channel, the bubble fields can be adjusted to balance the laser depletion and dephasing lengths. Bubble scaling laws for the deep channel are derived. Ultra-short pancake-like laser pulses lead to the highest energies of accelerated electrons per Joule of laser pulse energy.

  13. Lattice Location of Radioactive Probes in Semiconductors and Metals by Electron and Positron Channelling

    CERN Multimedia

    2002-01-01

    The channelling effect of decay-electrons and positrons is used for the localization of radioactive impurities implanted into single crystals. Because of the low implantation doses and the variety of different isotopes available at ISOLDE, this technique is especially suited for applications in semiconducting materials. \\\\ \\\\ Channelling measurements in Si, GaAs and GaP implanted with In-, Cd- and Xe-isotopes have demonstrated that impurity lattice sites can be studied directly after implantation without any annealing. The electron-channelling technique can be ideally combined with hyperfine interaction techniques like Moessbauer s This was shown for the formation of In-vacancy complexes in ion-implanted Ni. \\\\ \\\\ We intend to continue the lattice location measurements in semiconductors implanted with various radioactive impurities of Cd, In, Sn, Sb and Te.

  14. Quasi-phase-matched acceleration of electrons in a corrugated plasma channel

    Directory of Open Access Journals (Sweden)

    S. J. Yoon

    2012-08-01

    Full Text Available A laser pulse propagating in a corrugated plasma channel is composed of spatial harmonics whose phase velocities can be subluminal. The phase velocity of a spatial harmonic can be matched to the speed of a relativistic electron resulting in direct acceleration by the guided laser field in a plasma waveguide and linear energy gain over the interaction length. Here we examine the fully self-consistent interaction of the laser pulse and electron beam using particle-in-cell (PIC simulations. For low electron beam densities, we find that the ponderomotive force of the laser pulse pushes plasma channel electrons towards the propagation axis, which deflects the beam electrons. When the beam density is high, the space charge force of the beam drives the channel electrons off axis, providing collimation of the beam. In addition, we consider a ramped density profile for lowering the threshold energy for trapping in a subluminal spatial harmonic. By using a density ramp, the trapping energy for a normalized vector potential of a_{0}=0.1 is reduced from a relativistic factor γ_{0}=170 to γ_{0}=20.

  15. Coupled channel calculations for electron-positron pair production in collisions of heavy ions

    CERN Document Server

    Gail, M; Scheid, W

    2003-01-01

    Coupled channel calculations are performed for electron-positron pair production in relativistic collisions of heavy ions. For this purpose the wavefunction is expanded into different types of basis sets consisting of atomic wavefunctions centred around the projectile ion only and around both of the colliding nuclei. The results are compared with experimental data from Belkacem et al (1997 Phys. Rev. A 56 2807).

  16. Analysis of strain field around. beta. -hydride in Nb-H by Electron Channeling

    Energy Technology Data Exchange (ETDEWEB)

    Akune, K; Bulhoes, I A.M.

    1985-06-01

    The strain field in Nb-H system generated by the precipitation of ..beta..-hydride has been evaluated quantitatively by Electron Channeling experiment. The results were analyzed in terms of the effective deformation of the Levi-Mises solid by making use of an elasto-plastic model of the strain field around the misfitting cylindrical precipitate.

  17. Multi-GeV electron and positron channeling in bent silicon crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sushko, Gennady B., E-mail: sushko@fias.uni-frankfurt.de [Goethe-Universitat Frankfurt am Main, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); Korol, Andrei V. [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); St. Petersburg State Maritime University, Leninsky Ave. 101, 198262 St. Petersburg (Russian Federation); Solov’yov, Andrey V. [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); A.F. Ioffe Physical-Technical Institute, Politekhnicheskaya ul. 26, 194021 St. Petersburg (Russian Federation)

    2015-07-15

    The planar channeling of 3…20 GeV electrons and positrons in bent Si(1 1 1) crystal was simulated by means of the MBN EXPLORER software package. The results of the simulations are analyzed in terms of dechanneling length characterization, angular distribution of outgoing projectiles and radiation spectrum. The results of calculations are compared with the recent experimental data.

  18. Analysis of strain field around β-hydride in Nb-H by electron channeling

    International Nuclear Information System (INIS)

    Akune, K.; Bulhoes, I.A.M.

    1985-01-01

    The strain field in Nb-H system generated by the precipitation of β-hydride has been evaluated quantitatively by Electron Channelling experiment. The results were analyzed in terms of the effective deformation of the Levi-Mises solid by making use of an elasto-plastic model of the strain fiedl around the misfitting cylindrical precipitate. (Author) [pt

  19. The CLIC Test Facility (CTF3) which allowed the first electron beam recombination in order to multiply the RF frequency from 3 GHz up to 15 GHz.

    CERN Multimedia

    Maximilien Brice

    2002-01-01

    Photo 0210005_11: The CTF3 linac accelerates an electron beam up to 350 MeV. Photo 0210005_1: At the front, the yellow dipole is used for the spectrometer line. At the back, a doublet of blue quadrupole for the matching. Photo 0210005_03: The CTF3 transfer line between the electron linac and the isochronous ring. Photo 0210005_04: One arc of the EPA isochronous ring. Photo 0210005_06: The CTF3 bunching system. The first RF wave guide feeds the Pre-Buncher while the second RF wave guide feeds the Buncher. They provide a bunched electron beam at 4 MeV. The blue magnet is a solenoid around the Buncher. Photo 0210005_07: A LIL accelerating structure used for CTF3. It is 4.5 meters long and provides an energy gain of 45 MeV. One can see 3 quadrupoles around the RF structure.

  20. Determination of local absolute detection efficiency of a ceratron with 55Fe Auger electrons

    International Nuclear Information System (INIS)

    Mori, C.; Sugiyama, T.; Watanabe, T.

    1983-01-01

    The local absolute detection efficiency of a Ceratron (channel electron multiplier made of ceramics) was determined with collimated Mn K Auger electrons ( 5 keV) emitted from 55 Fe as a function of electron incident position and applied voltage. The local efficiency at the channel inlet did not depend so much on the applied voltage. The efficiency at the funnel increased with the applied voltage, while it was always lower than that at the channel inlet. (orig.)

  1. Effective switching frequency multiplier inverter

    Science.gov (United States)

    Su, Gui-Jia [Oak Ridge, TN; Peng, Fang Z [Okemos, MI

    2007-08-07

    A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

  2. FdC1 and Leaf-Type Ferredoxins Channel Electrons From Photosystem I to Different Downstream Electron Acceptors.

    Science.gov (United States)

    Guan, Xiaoqian; Chen, Shuai; Voon, Chia Pao; Wong, Kam-Bo; Tikkanen, Mikko; Lim, Boon L

    2018-01-01

    Plant-type ferredoxins in Arabidopsis transfer electrons from the photosystem I to multiple redox-driven enzymes involved in the assimilation of carbon, nitrogen, and sulfur. Leaf-type ferredoxins also modulate the switch between the linear and cyclic electron routes of the photosystems. Recently, two novel ferredoxin homologs with extra C-termini were identified in the Arabidopsis genome (AtFdC1, AT4G14890; AtFdC2, AT1G32550). FdC1 was considered as an alternative electron acceptor of PSI under extreme ferredoxin-deficient conditions. Here, we showed that FdC1 could interact with some, but not all, electron acceptors of leaf-type Fds, including the ferredoxin-thioredoxin reductase (FTR), sulfite reductase (SiR), and nitrite reductase (NiR). Photoreduction assay on cytochrome c and enzyme assays confirmed its capability to receive electrons from PSI and donate electrons to the Fd-dependent SiR and NiR but not to the ferredoxin-NADP + oxidoreductase (FNR). Hence, FdC1 and leaf-type Fds may play differential roles by channeling electrons from photosystem I to different downstream electron acceptors in photosynthetic tissues. In addition, the median redox potential of FdC1 may allow it to receive electrons from FNR in non-photosynthetic plastids.

  3. Overscreening-underscreening transition in the two-channel Kondo model induced by electron-electron repulsion

    International Nuclear Information System (INIS)

    Zhang Yumei; Chen Hong.

    1995-09-01

    The effects of the repulsion between the electrons on the two-channel Kondo problem are studied by use of the bosonization technique. Following Emery and Kivelson, we define a special case in the spin density wave sector, in which the impurity spin is actually detached from the dynamics of the electrons. The model is thus mapped to a local Sine-Gordon system. For weak repulsion, the basic features of the overscreening picture are maintained. However, at sufficient strong repulsion the system is driven into the weak coupling regime, hence an overscreening-underscreening transition emerges. (author). 22 refs

  4. Theoretical study of the electron stopping power in ion planar channeling

    International Nuclear Information System (INIS)

    Haymann, P.

    1974-01-01

    A theory recently developed by the authors for slow and fast electrons is shown to be also applicable to channeled ions and to explain the experimental results about electron loss phenomena as a whole. The theory is based on the fundamental hypothesis of the nonadiabaticity of the ion-target interactions. How essential an exponential form of the interaction pseudo-potential is in explaining the energy exchange mechanism at the walls may be deduced from a quasi-classical development of the quantum model. The theory also allows a number of new experiments to be envisaged in the field of surface electron states [fr

  5. Readout ASICs and Electronics for the 144-channel HAPDs for the Aerogel RICH at Belle II

    Science.gov (United States)

    Nishida, S.; Adachi, I.; Ikeda, H.; Hara, K.; Iijima, T.; Iwata, S.; Korpar, S.; Križan, P.; Kuroda, E.; Pestotnik, R.; Seljak, A.; Sumiyoshi, T.; Takagaki, H.

    The particle identification (PID) device in the endcap of the Belle detector will be upgraded to a ring imaging Cherenkov counter (RICH) using aerogel as a radiator at the Belle II experiment. We develop the electronics to read out the 70,000 channels of hit information from the 144-channel hybrid avalanche photodetectors (HAPD), of the aerogel RICH detector. A readout ASIC is developed to digitize the HAPD signals, and was used in a beam test with the prototype detector. The performance and plan of the ASIC is reported in this study. We have also designed the readout electronics for the aerogel RICH, which consist of front-end boards with the ASICs merger boards to collect data from the front-end boards. A front-end board that fits in the actual available space for the aerogel RICH electronics was produced.

  6. Numerical study of the generation of runaway electrons in a gas diode with a hot channel

    Energy Technology Data Exchange (ETDEWEB)

    Lisenkov, V. V., E-mail: lisenkov@iep.uran.ru [Institute of Electrophysics UrB RAS, 106 Amundsena St., Ekaterinburg 620012 (Russian Federation); Ural Federal University, 19 Mira St., Ekaterinburg 620002 (Russian Federation); Shklyaev, V. A., E-mail: shklyaev@to.hcei.tsc.ru [Institute of High Current Electronics SD RAS, 2/3 Akademichesky Avenue, 634055 Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Avenue, 634050 Tomsk (Russian Federation)

    2015-11-15

    A new method for increasing the efficiency of runaway electron beam generation in atmospheric pressure gas media has been suggested and theoretically proved. The method consists of creating a hot region (e.g., a spark channel or a laser plume) with a decreased numerical density of gas molecules (N) near the cathode. In this method, the ratio E/N (E—electric field strength) is increased by decreasing N instead of increasing E, as has been done in the past. The numerical model that is used allows the simultaneous calculation of the formation of a subnanosecond gas discharge and the generation of runaway electrons in gas media. The calculations have demonstrated the possibility of obtaining current pulses of runaway electrons with amplitudes of hundred of amperes and durations of more than 100 ps. The influence of the hot channel geometry on the parameters of the generated beam has been investigated.

  7. Electron-electron scattering-induced channel hot electron injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors with high-k/metal gate stacks

    International Nuclear Information System (INIS)

    Tsai, Jyun-Yu; Liu, Kuan-Ju; Lu, Ying-Hsin; Liu, Xi-Wen; Chang, Ting-Chang; Chen, Ching-En; Ho, Szu-Han; Tseng, Tseung-Yuen; Cheng, Osbert; Huang, Cheng-Tung; Lu, Ching-Sen

    2014-01-01

    This work investigates electron-electron scattering (EES)-induced channel hot electron (CHE) injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors (n-MOSFETs) with high-k/metal gate stacks. Many groups have proposed new models (i.e., single-particle and multiple-particle process) to well explain the hot carrier degradation in nanoscale devices and all mechanisms focused on Si-H bond dissociation at the Si/SiO 2 interface. However, for high-k dielectric devices, experiment results show that the channel hot carrier trapping in the pre-existing high-k bulk defects is the main degradation mechanism. Therefore, we propose a model of EES-induced CHE injection to illustrate the trapping-dominant mechanism in nanoscale n-MOSFETs with high-k/metal gate stacks.

  8. Determination of gas temperature in the plasmatron channel according to the known distribution of electronic temperature

    Directory of Open Access Journals (Sweden)

    Gerasimov Alexander V.

    2013-01-01

    Full Text Available An analytical method to calculate the temperature distribution of heavy particles in the channel of the plasma torch on the known distribution of the electronic temperature has been proposed. The results can be useful for a number of model calculations in determining the most effective conditions of gas blowing through the plasma torch with the purpose of heating the heavy component. This approach allows us to understand full details about the heating of cold gas, inpouring the plasma, and to estimate correctly the distribution of the gas temperature inside the channel.

  9. The long-run relationship between the Japanese credit and money multipliers

    OpenAIRE

    Mototsugu Fukushige

    2013-01-01

    The standard argument is that while money creation and credit creation have different channels, they provide the same theoretical size of multipliers. However, there is usually some difference in practice. Consequently, in this paper we investigate the long-run relationship between the credit and money multipliers in Japan.

  10. Automation of electron channeling investigations into crystals on the experimental stand

    International Nuclear Information System (INIS)

    Kolodin, L.G.; Kupchishin, A.A.; Bunegin, V.V.

    1995-01-01

    Automated control system of technological processes of the experimental stand is proposed for electron channeling investigation into crystals. The system is proposed for stand control automation and registration of corresponding radiations. There are four main parts in stand complex: Ehlu-6 type electron accelerator; forming and transporting system of electron beams; goniometer system; radiation detection system. Purposes of the automated system creation are following: - improvement of EhLU accelerator operating stability by of automation stabilization of its parameters; - quality improvement of electron beam monochromatization by of automation of monochromator electromagnet control; - simplification of crystal adjustment process relatively of primary electron beam and crystal transporting to the position by of goniometer automation control; - providing of automating collection and processing of data of physical experiments

  11. Calculating the electron temperature in the lightning channel by continuous spectrum

    Science.gov (United States)

    Xiangcheng, DONG; Jianhong, CHEN; Xiufang, WEI; Ping, YUAN

    2017-12-01

    Based on the theory of plasma continuous radiation, the relationship between the emission intensity of bremsstrahlung and recombination radiation and the plasma electron temperature is obtained. During the development process of a return stroke of ground flash, the intensity of continuous radiation spectrum is separated on the basis of the spectrums with obviously different luminous intensity at two moments. The electron temperature of the lightning discharge channel is obtained through the curve fitting of the continuous spectrum intensity. It is found that electron temperature increases with the increase of wavelength and begins to reduce after the peak. The peak temperature of the two spectra is close to 25 000 K. To be compared with the result of discrete spectrum, the electron temperature is fitted by the O I line and N II line of the spectrum respectively. The comparison shows that the high temperature value is in good agreement with the temperature of the lightning core current channel obtained from the ion line information, and the low temperature at the high band closes to the calculation result of the atomic line, at a low band is lower than the calculation of the atomic line, which reflects the temperature of the luminous channel of the outer corona.

  12. Digitally controlled high-performance dc SQUID readout electronics for a 304-channel vector magnetometer

    Science.gov (United States)

    Bechstein, S.; Petsche, F.; Scheiner, M.; Drung, D.; Thiel, F.; Schnabel, A.; Schurig, Th

    2006-06-01

    Recently, we have developed a family of dc superconducting quantum interference device (SQUID) readout electronics for several applications. These electronics comprise a low-noise preamplifier followed by an integrator, and an analog SQUID bias circuit. A highly-compact low-power version with a flux-locked loop bandwidth of 0.3 MHz and a white noise level of 1 nV/√Hz was specially designed for a 304-channel low-Tc dc SQUID vector magnetometer, intended to operate in the new Berlin Magnetically Shielded Room (BMSR-2). In order to minimize the space needed to mount the electronics on top of the dewar and to minimize the power consumption, we have integrated four electronics channels on one 3 cm × 10 cm sized board. Furthermore we embedded the analog components of these four channels into a digitally controlled system including an in-system programmable microcontroller. Four of these integrated boards were combined to one module with a size of 4 cm × 4 cm × 16 cm. 19 of these modules were implemented, resulting in a total power consumption of about 61 W. To initialize the 304 channels and to service the system we have developed software tools running on a laptop computer. By means of these software tools the microcontrollers are fed with all required data such as the working points, the characteristic parameters of the sensors (noise, voltage swing), or the sensor position inside of the vector magnetometer system. In this paper, the developed electronics including the software tools are described, and first results are presented.

  13. Digitally controlled high-performance dc SQUID readout electronics for a 304-channel vector magnetometer

    International Nuclear Information System (INIS)

    Bechstein, S; Petsche, F; Scheiner, M; Drung, D; Thiel, F; Schnabel, A; Schurig, Th

    2006-01-01

    Recently, we have developed a family of dc superconducting quantum interference device (SQUID) readout electronics for several applications. These electronics comprise a low-noise preamplifier followed by an integrator, and an analog SQUID bias circuit. A highly-compact low-power version with a flux-locked loop bandwidth of 0.3 MHz and a white noise level of 1 nV/√Hz was specially designed for a 304-channel low-T c dc SQUID vector magnetometer, intended to operate in the new Berlin Magnetically Shielded Room (BMSR-2). In order to minimize the space needed to mount the electronics on top of the dewar and to minimize the power consumption, we have integrated four electronics channels on one 3 cm x 10 cm sized board. Furthermore we embedded the analog components of these four channels into a digitally controlled system including an in-system programmable microcontroller. Four of these integrated boards were combined to one module with a size of 4 cm x 4 cm x 16 cm. 19 of these modules were implemented, resulting in a total power consumption of about 61 W. To initialize the 304 channels and to service the system we have developed software tools running on a laptop computer. By means of these software tools the microcontrollers are fed with all required data such as the working points, the characteristic parameters of the sensors (noise, voltage swing), or the sensor position inside of the vector magnetometer system. In this paper, the developed electronics including the software tools are described, and first results are presented

  14. Digitally controlled high-performance dc SQUID readout electronics for a 304-channel vector magnetometer

    Energy Technology Data Exchange (ETDEWEB)

    Bechstein, S [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Petsche, F [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Scheiner, M [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Drung, D [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Thiel, F [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Schnabel, A [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Schurig, Th [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany)

    2006-06-01

    Recently, we have developed a family of dc superconducting quantum interference device (SQUID) readout electronics for several applications. These electronics comprise a low-noise preamplifier followed by an integrator, and an analog SQUID bias circuit. A highly-compact low-power version with a flux-locked loop bandwidth of 0.3 MHz and a white noise level of 1 nV/{radical}Hz was specially designed for a 304-channel low-T{sub c} dc SQUID vector magnetometer, intended to operate in the new Berlin Magnetically Shielded Room (BMSR-2). In order to minimize the space needed to mount the electronics on top of the dewar and to minimize the power consumption, we have integrated four electronics channels on one 3 cm x 10 cm sized board. Furthermore we embedded the analog components of these four channels into a digitally controlled system including an in-system programmable microcontroller. Four of these integrated boards were combined to one module with a size of 4 cm x 4 cm x 16 cm. 19 of these modules were implemented, resulting in a total power consumption of about 61 W. To initialize the 304 channels and to service the system we have developed software tools running on a laptop computer. By means of these software tools the microcontrollers are fed with all required data such as the working points, the characteristic parameters of the sensors (noise, voltage swing), or the sensor position inside of the vector magnetometer system. In this paper, the developed electronics including the software tools are described, and first results are presented.

  15. A Synthesis of Star Calibration Techniques for Ground-Based Narrowband Electron-Multiplying Charge-Coupled Device Imagers Used in Auroral Photometry

    Science.gov (United States)

    Grubbs, Guy II; Michell, Robert; Samara, Marilia; Hampton, Don; Jahn, Jorg-Micha

    2016-01-01

    A technique is presented for the periodic and systematic calibration of ground-based optical imagers. It is important to have a common system of units (Rayleighs or photon flux) for cross comparison as well as self-comparison over time. With the advancement in technology, the sensitivity of these imagers has improved so that stars can be used for more precise calibration. Background subtraction, flat fielding, star mapping, and other common techniques are combined in deriving a calibration technique appropriate for a variety of ground-based imager installations. Spectral (4278, 5577, and 8446 A ) ground-based imager data with multiple fields of view (19, 47, and 180 deg) are processed and calibrated using the techniques developed. The calibration techniques applied result in intensity measurements in agreement between different imagers using identical spectral filtering, and the intensity at each wavelength observed is within the expected range of auroral measurements. The application of these star calibration techniques, which convert raw imager counts into units of photon flux, makes it possible to do quantitative photometry. The computed photon fluxes, in units of Rayleighs, can be used for the absolute photometry between instruments or as input parameters for auroral electron transport models.

  16. Low emittance design of the electron gun and the focusing channel of the Compact Linear Collider drive beam

    Directory of Open Access Journals (Sweden)

    M. Dayyani Kelisani

    2017-04-01

    Full Text Available For the Compact Linear Collider project at CERN, the power for the main linacs is extracted from a drive beam generated from a high current electron source. The design of the electron source and its subsequent focusing channel has a great impact on the beam dynamic considerations of the drive beam. We report the design of a thermionic electron source and the subsequent focusing channels with the goal of production of a high quality beam with a very small emittance.

  17. Structure of the TRPV1 ion channel determined by electron cryo-microscopy.

    Science.gov (United States)

    Liao, Maofu; Cao, Erhu; Julius, David; Cheng, Yifan

    2013-12-05

    Transient receptor potential (TRP) channels are sensors for a wide range of cellular and environmental signals, but elucidating how these channels respond to physical and chemical stimuli has been hampered by a lack of detailed structural information. Here we exploit advances in electron cryo-microscopy to determine the structure of a mammalian TRP channel, TRPV1, at 3.4 Å resolution, breaking the side-chain resolution barrier for membrane proteins without crystallization. Like voltage-gated channels, TRPV1 exhibits four-fold symmetry around a central ion pathway formed by transmembrane segments 5-6 (S5-S6) and the intervening pore loop, which is flanked by S1-S4 voltage-sensor-like domains. TRPV1 has a wide extracellular 'mouth' with a short selectivity filter. The conserved 'TRP domain' interacts with the S4-S5 linker, consistent with its contribution to allosteric modulation. Subunit organization is facilitated by interactions among cytoplasmic domains, including amino-terminal ankyrin repeats. These observations provide a structural blueprint for understanding unique aspects of TRP channel function.

  18. Multiply charged ions from solid substances with the mVINIS Ion Source

    International Nuclear Information System (INIS)

    Dragani, I; Nedeljkovi, T; Jovovi, J; Siljegovic, M; Dobrosavljevic, A

    2007-01-01

    We have used the well known metal-ions-from-volatile-compounds (MIVOC) method at the mVINIS Ion Source to produce the multiply charged ion beams form solid substances. Based on this method the very intense and stable multiply charged ion beams of several solid substances having the high melting points were extracted. The ion yields and the spectra of multiply charged ion beams obtained from solid materials like Fe and Hf will be presented. We have utilized the multiply charged ion beams from solid substances to irradiate the polymers, fullerenes and glassy carbon at the low energy channel for modification of materials

  19. Multi-Channel Electronically Scanned Cryogenic Pressure Sensor And Method For Making Same

    Science.gov (United States)

    Chapman, John J. (Inventor); Hopson, Purnell, Jr. (Inventor); Holloway, Nancy M. (Inventor)

    2001-01-01

    A miniature, multi-channel, electronically scanned pressure measuring device uses electrostatically bonded silicon dies in a multi-element array. These dies are bonded at specific sites on a glass, pre-patterned substrate. Thermal data is multiplexed and recorded on each individual pressure measuring diaphragm. The device functions in a cryogenic environment without the need of heaters to keep the sensor at constant temperatures.

  20. Kinetic description of a wiggler pumped ion-channel free electron laser

    International Nuclear Information System (INIS)

    Mehdian, H; Raghavi, A

    2006-01-01

    The wiggler pumped ion-channel free electron laser (WPIC-FEL) is treated and the classes of possible single-particle electron trajectories in this configuration are discussed in the paper. A new region of orbital stability is seen in the negative mass regime. A kinetic description of WPIC-FEL is given. Vlasov-Maxwell equations are solved to get the linear gain in a tenuous-beam limit, where the beam plasma frequency is much less than the radiation frequency and the self-field effects can be ignored

  1. Sausage instabilities in electron current channels and the problem of fast ignition

    International Nuclear Information System (INIS)

    Das, A.

    2002-01-01

    In the fast ignition concept of laser fusion, an intense picosecond laser pulse incident on an overdense pellet is absorbed by nonlinear mechanisms and gets converted into inward propagating fast electron currents. PIC simulations show that the return shielding currents due to cold plasma interact with the incoming currents and intense Weibel, tearing and coalescence instabilities take place, which organize the current into a few current channels. The stability of these current channels is thus a topic of great interest. We have carried out linear and nonlinear studies of 2 - dimensional sausage instabilities of a slab model of the current channels in the framework of electron magnetohydrodynamic fluid approximation. The analytic calculations and numerical simulations for some simple velocity profiles show the presence of linear instability driven by velocity shear. Nonlinear studies on the saturation of instabilities and their reaction back on the relaxation of the velocity profile have also been made. A discussion of the consequences of such EMHD turbulence induced relaxation and stopping of fast electrons, for the fast ignition concept will be presented. (author)

  2. High quality electron beams from a plasma channel guided laser wakefield accelerator

    International Nuclear Information System (INIS)

    Geddes, C.G.R.; Toth, Cs.; Tilborg, J. van; Esarey, E.; Schroeder, C.B.; Bruhwiler, D.; Nieter, C.; Cary, J.; Leemans, W.P.

    2004-01-01

    Laser driven accelerators, in which particles are accelerated by the electric field of a plasma wave driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV/m. These fields are thousands of times those achievable in conventional radiofrequency (RF) accelerators, spurring interest in laser accelerators as compact next generation sources of energetic electrons and radiation. To date however, acceleration distances have been severely limited by lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance results in low energy beams with 100% electron energy spread, limiting applications. Here we demonstrate that a relativistically intense laser can be guided by a preformed plasma density channel and that the longer propagation distance can result in electron beams of percent energy spread with low emittance and increased energy, containing >10 9 electrons above 80 MeV. The preformed plasma channel technique forms the basis of a new class of accelerators, combining beam quality comparable to RF accelerators with the high gradients of laser accelerators to produce compact tunable high brightness electron and radiation sources

  3. Micro-channel plate detector for ultra-fast relativistic electron diffraction

    International Nuclear Information System (INIS)

    Musumeci, P.; Moody, J.T.; Scoby, C.M.; Gutierrez, M.S.; Bender, H.A.; Hilko, B.; Kruschwitz, C.A.; Wilcox, N.S.

    2011-01-01

    Using relativistic ultra-short electron beams to obtain single-shot diffraction patterns holds the promise to yield real-time resolution of atomic motion in an easily accessible environment, such as a university laboratory, at a fraction of the cost of fourth-generation X-ray sources. One of the main issues in bringing this technique to full maturity is the development of efficient detector systems to record the diffraction pattern using a few MeV electron beams. Low noise, high spatial resolution, and single-electron detection capability are all characteristics of an ideal detector. In this paper, we compare the performances of a traditional fluorescent phosphor screen with a detection system based on the micro-channel plate (MCP). Since MCPs are typically used with lower energy electron beams, these tests constitute one of the few experimental data points available on the use of these devices with MeV energy beams.

  4. Micro-channel plate detector for ultra-fast relativistic electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Musumeci, P., E-mail: musumeci@physics.ucla.edu [UCLA Department of Physics and Astronomy, 475 Portola Plaza, Los Angeles, CA, 90095-1547 (United States); Moody, J.T.; Scoby, C.M.; Gutierrez, M.S. [UCLA Department of Physics and Astronomy, 475 Portola Plaza, Los Angeles, CA, 90095-1547 (United States); Bender, H.A.; Hilko, B.; Kruschwitz, C.A.; Wilcox, N.S. [National Security Technologies, LLC, Los Alamos Operations, Los Alamos, NM (United States)

    2011-05-01

    Using relativistic ultra-short electron beams to obtain single-shot diffraction patterns holds the promise to yield real-time resolution of atomic motion in an easily accessible environment, such as a university laboratory, at a fraction of the cost of fourth-generation X-ray sources. One of the main issues in bringing this technique to full maturity is the development of efficient detector systems to record the diffraction pattern using a few MeV electron beams. Low noise, high spatial resolution, and single-electron detection capability are all characteristics of an ideal detector. In this paper, we compare the performances of a traditional fluorescent phosphor screen with a detection system based on the micro-channel plate (MCP). Since MCPs are typically used with lower energy electron beams, these tests constitute one of the few experimental data points available on the use of these devices with MeV energy beams.

  5. Transport of long-pulse relativistic electron beams in preformed plasma channels in the ion focus regime

    International Nuclear Information System (INIS)

    Miller, J.D.

    1989-01-01

    Experiments have been performed demonstrating efficient transport of long-pulse (380 ns), high-current (200 A), relativistic electron beams (REBs) in preformed plasma channels in the ion focus regime (IFR). Plasma channels were created by low-energy ( e , and channel ion mass, in agreement with theoretical values predicted for the ion hose instability. Microwave emission has also been observed indicative of REB-plasma electron two-stream instability. Plasma channel density measurements indicate that the two-stream instability can become dominant for measured f e values slightly above unity. The author has introduced a theoretical analysis for high-current REB transport and modulation in axially periodic IFR plasma channels. Analytic expression for the electric field are found for the case of a cosine modulation of the channel ion density. Two different types of channels are considered: (i) periodic beam-induced ionization channels, and (ii) periodic plasma slab channels created by an external source. Analytical conditions are derived for the matched radius of the electron beam and for approximate beam envelope motion using a 'smooth' approximation. Numerical solutions to the envelope equation show that by changing the wavelength or the amplitude of the space-charge neutralization fraction of the ion channel density modulation, the beam can be made to focus and diverge, or to undergo stable, modulated transport

  6. Simulation of planar channeling-radiation spectra of relativistic electrons and positrons channeled in a diamond-structure or tungsten single crystal (classical approach)

    International Nuclear Information System (INIS)

    Azadegan, B.; Wagner, W.

    2015-01-01

    We present a Mathematica package for simulation of spectral-angular distributions and energy spectra of planar channeling radiation of relativistic electrons and positrons channeled along major crystallographic planes of a diamond-structure or tungsten single crystal. The program is based on the classical theory of channeling radiation which has been successfully applied to study planar channeling of light charged particles at energies higher than 100 MeV. Continuous potentials for different planes of diamond, Si, Ge and W single crystals are calculated using the Doyle–Turner approximation to the atomic scattering factor and taking thermal vibrations of the crystal atoms into account. Numerical methods are applied to solve the classical one-dimensional equation of motion. The code is designed to calculate the trajectories, velocities and accelerations of electrons (positrons) channeled by the planar continuous potential. In the framework of classical electrodynamics, these data allow realistic simulations of spectral-angular distributions and energy spectra of planar channeling radiation. Since the generated output is quantitative, the results of calculation may be useful, e.g., for setup configuration and crystal alignment in channeling experiments, for the study of the dependence of channeling radiation on the input parameters of particle beams with respect to the crystal orientation, but also for the simulation of positron production by means of pair creation what is mandatory for the design of efficient positron sources necessary in high-energy and collider physics. Although the classical theory of channeling is well established for long time, there is no adequate library program for simulation of channeling radiation up to now, which is commonly available, sufficiently simple and effective to employ and, therefore, of benefit as for special investigations as for a quick overview of basic features of this type of radiation

  7. Enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target

    Science.gov (United States)

    Ji, Yanling; Duan, Tao; Zhou, Weimin; Li, Boyuan; Wu, Fengjuan; Zhang, Zhimeng; Ye, Bin; Wang, Rong; Wu, Chunrong; Tang, Yongjian

    2018-02-01

    An enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target is investigated using two-dimensional particle-in-cell simulations. The target consists of a cone attached to a double-layer hollow channel with a near-critical-density inner layer. The periodic electron beams are generated by the combination of ponderomotive force and longitudinal laser electric field. Then a stable electron propagation is achieved in the double-layer channel over a much longer distance without evident divergency, compared with a normal cone-channel target. Detailed simulations show that the much better long-distance collimation and guidance of energetic electrons is attributed to the much stronger electromagnetic fields at the inner wall surfaces. Furthermore, a continuous electron acceleration is obtained by the more intense laser electric fields and extended electron acceleration length in the channel. Our investigation shows that by employing this advanced target, both the forward-going electron energy flux in the channel and the energy coupling efficiency from laser to electrons are about threefold increased in comparison with the normal case.

  8. Enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target

    Directory of Open Access Journals (Sweden)

    Yanling Ji

    2018-02-01

    Full Text Available An enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target is investigated using two-dimensional particle-in-cell simulations. The target consists of a cone attached to a double-layer hollow channel with a near-critical-density inner layer. The periodic electron beams are generated by the combination of ponderomotive force and longitudinal laser electric field. Then a stable electron propagation is achieved in the double-layer channel over a much longer distance without evident divergency, compared with a normal cone-channel target. Detailed simulations show that the much better long-distance collimation and guidance of energetic electrons is attributed to the much stronger electromagnetic fields at the inner wall surfaces. Furthermore, a continuous electron acceleration is obtained by the more intense laser electric fields and extended electron acceleration length in the channel. Our investigation shows that by employing this advanced target, both the forward-going electron energy flux in the channel and the energy coupling efficiency from laser to electrons are about threefold increased in comparison with the normal case.

  9. Lagrange multipliers and gravitational theory

    International Nuclear Information System (INIS)

    Elston, F.D.

    1977-01-01

    The Lagrange multiplier variational method is extended to nonlinear Lagrangians in a Riemann space, where it is shown explicitly for the quadratic Lagrangians that, as expected, this approach is equivalent to the Hilbert variational method. It is not, in general, equivalent to the Palatini variational method. The nonvanishing Lagrange multipliers for the quadratic Lagrangians are explicitly obtained in covariant form. A similiar analysis is then carried out in a Riemann--Cartan torsional metric space for the specific Lagrangians g/sup 1/2/R tilde and g/sup 1/2/R/sub uv/tilde R/sup uv/tilde. The possible relevance of the R/sub uv/R/sup u anti v/ invariant to an action-principle formulation of the Rainich--Misner--Wheeler (RMW) already-unified theory is also discussed. It is then pointed out how a different use of the Lagrange multiplier technique in the language of the 3 + 1 canonical formalism developed by Arnowitt, Deser, and Misner (ADM) permits the recasting of the equations of motion for quadratic and general higher-order invariants into the ADM canonical formalism. In general, without this Lagrange multiplier approach, the higher-order ADM problem could not be solved. This is done explicitly for the simplest quadratic Langrangian g/sup 1/2/R 2 as an example

  10. Multiplied Environmental Literacy. Final Report.

    Science.gov (United States)

    Buethe, Chris

    This booklet presents a pupil-oriented program designed to increase the environmental literacy of teachers and students in Indiana schools through a programmed multiplier effect. Junior and senior high school science teachers were prepared to teach students the meanings of 44 selected environmental terms and related concepts. Those teachers then…

  11. Increase in electron mobility of InGaAs/InP composite channel high electron mobility transistor structure due to SiN passivation

    International Nuclear Information System (INIS)

    Liu Yuwei; Wang Hong; Radhakrishnan, K.

    2007-01-01

    The influence of silicon nitride passivation on electron mobility of InGaAs/InP composite channel high electron mobility transistor structure has been studied. Different from the structures with single InGaAs channel, an increase in effective mobility μ e with a negligible change of sheet carrier density n s after SiN deposition is clearly observed in the composite channel structures. The enhancement of μ e could be explained under the framework of electrons transferring from the InP sub-channel into InGaAs channel region due to the energy band bending at the surface region caused by SiN passivation, which is further confirmed by low temperature photoluminescence measurements

  12. Features of destruction of solids by laser radiation in process of formation of multiply charged ions

    International Nuclear Information System (INIS)

    Bedilov, R.M.; Bedilov, M.R.; Sabitov, M.M.; Matnazarov, A.; Niyozov, B.

    2004-01-01

    Full text: It is known, under interaction of laser radiation with solid surface a power density q > 0.01 W/cm 2 are observed destruction of a solid and issue of electrons, ions, neutrals, neutrons, plasmas, and also radiation in a wide ranges of a spectra. Despite of a plenty of works, devoted to study of processes of interaction, the studies of feature of destruction of solids by laser beam in process of formation multiply charged ions are insufficiently investigated. The results of study feature of destruction of solids by laser radiation in process of formation multiply charged ions are given in this work. In our experiments, we used the mass spectrometer with single-channel laser radiation. The laser installation had the following parameters: a power density of laser radiation q=(0.1-50) GW/cm 2 ; the angle of incidence a=18 deg. to the target surface Al, (W). It was obtained experimentally dynamics of morphology of destruction and also mass - charge and energy spectra of multiply charged ions formed under interaction of laser radiation with Al (W) in the intensity range q=(0.1-50) GW/cm 2 . These studies showed features of destruction Al(W) by laser radiation, i.e. invariable of value evaporation mass from a surface of a solid increase as the laser intensity q. But thus temperature a pair increases in accordance with increase of flow density of a laser radiation. Increase of temperature the pair gives in formation of multiply charged plasma. It is typical that, as q of the laser increases the maximum charge number of ions in laser plasma considerably increase and their energy spectra extend toward higher energies. For example, under q=0.1 GW/cm 2 and 50 GW/cm 2 the maximum charge number of ions Al (W) are equal to Z max = 1 and 7, respectively. From the experimental data obtained, we can conclude that, the formed multiply charged plasma practically completely absorption laser radiation and 'shielding' a target surface for various metals at power densities

  13. Electron temperature measurements during electron cyclotron heating on PDX using a ten channel grating polychromator

    International Nuclear Information System (INIS)

    Cavallo, A.; Hsuan, H.; Boyd, D.; Grek, B.; Johnson, D.; Kritz, A.; Mikkelsen, D.; LeBlanc, B.; Takahashi, H.

    1984-10-01

    During first harmonic electron cyclotron heating (ECH) on the Princeton Divertor Experiment (PDX) (R 0 = 137 cm, a = 40 cm), electron temperature was monitored using a grating polychromator which measured second harmonic electron cyclotron emission from the low field side of the tokamak. Interference from the high power heating pulse on the broadband detectors in the grating instrument was eliminated by using a waveguide filter in the transmission line which brought the emission signal to the grating instrument. Off-axis (approx. 4 cm) location of the resonance zone resulted in heating without sawtooth or m = 1 activity. However, heating with the resonance zone at the plasma center caused very large amplitude sawteeth accompanied by strong m = 1 activity: ΔT/T/sub MAX/ approx. = 0.41, sawtooth period approx. = 4 msec, m = 1 period approx. = 90 μ sec, (11 kHz). This is the first time such intense MHD activity driven by ECH has been observed. (For both cases there was no sawtooth activity in the ohmic phase of the discharge before ECH.) At very low densities there is a clear indication that a superthermal electron population is created during ECH

  14. Microfluidic CODES: a scalable multiplexed electronic sensor for orthogonal detection of particles in microfluidic channels.

    Science.gov (United States)

    Liu, Ruxiu; Wang, Ningquan; Kamili, Farhan; Sarioglu, A Fatih

    2016-04-21

    Numerous biophysical and biochemical assays rely on spatial manipulation of particles/cells as they are processed on lab-on-a-chip devices. Analysis of spatially distributed particles on these devices typically requires microscopy negating the cost and size advantages of microfluidic assays. In this paper, we introduce a scalable electronic sensor technology, called microfluidic CODES, that utilizes resistive pulse sensing to orthogonally detect particles in multiple microfluidic channels from a single electrical output. Combining the techniques from telecommunications and microfluidics, we route three coplanar electrodes on a glass substrate to create multiple Coulter counters producing distinct orthogonal digital codes when they detect particles. We specifically design a digital code set using the mathematical principles of Code Division Multiple Access (CDMA) telecommunication networks and can decode signals from different microfluidic channels with >90% accuracy through computation even if these signals overlap. As a proof of principle, we use this technology to detect human ovarian cancer cells in four different microfluidic channels fabricated using soft lithography. Microfluidic CODES offers a simple, all-electronic interface that is well suited to create integrated, low-cost lab-on-a-chip devices for cell- or particle-based assays in resource-limited settings.

  15. Analyses of electron runaway in front of the negative streamer channel

    Science.gov (United States)

    Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.; Neubert, T.; Chanrion, O.

    2017-08-01

    X-ray and γ-ray emissions, observed in correlation with negative leaders of lightning and long sparks of high-voltage laboratory experiments, are conventionally connected with the bremsstrahlung of high-energy runaway electrons (REs). Here we extend a focusing mechanism, analyzed in our previous paper, which allows the electric field to reach magnitudes, required for a generation of significant RE fluxes and associated bremsstrahlung, when the ionization wave propagates in a narrow, ionized channel created by a previous streamer. Under such conditions we compute the production rate of REs per unit streamer length as a function of the streamer velocity and predict that, once a streamer is formed with the electric field capable of producing REs ahead of the streamer front, the ionization induced by the REs is capable of creating an ionized channel that allows for self-sustained propagation of the RE-emitting ionization wave independent of the initial electron concentration. Thus, the streamer coronas of the leaders are probable sources of REs producing the observed high-energy radiation. To prove these predictions, new simulations are planned, which would show explicitly that the preionization in front of the channel via REs will lead to the ionization wave propagation self-consistent with RE generation.

  16. Channeling experiments at planar diamond and silicon single crystals with electrons from the Mainz Microtron MAMI

    Science.gov (United States)

    Backe, H.; Lauth, W.; Tran Thi, T. N.

    2018-04-01

    Line structures were observed for (110) planar channeling of electrons in a diamond single crystal even at a beam energy of 180 MeV . This observation motivated us to initiate dechanneling length measurements as function of the beam energy since the occupation of quantum states in the channeling potential is expected to enhance the dechanneling length. High energy loss signals, generated as a result of emission of a bremsstrahlung photon with about half the beam energy at channeling of 450 and 855 MeV electrons, were measured as function of the crystal thickness. The analysis required additional assumptions which were extracted from the numerical solution of the Fokker-Planck equation. Preliminary results for diamond are presented. In addition, we reanalyzed dechanneling length measurements at silicon single crystals performed previously at the Mainz Microtron MAMI at beam energies between 195 and 855 MeV from which we conclude that the quality of our experimental data set is not sufficient to derive definite conclusions on the dechanneling length. Our experimental results are below the predictions of the Fokker-Planck equation and somewhat above the results of simulation calculations of A. V. Korol and A. V. Solov'yov et al. on the basis of the MBN Explorer simulation package. We somehow conservatively conclude that the prediction of the asymptotic dechanneling length on the basis of the Fokker-Planck equation represents an upper limit.

  17. Observation of strong reflection of electron waves exiting a ballistic channel at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Vaz, Canute I.; Campbell, Jason P.; Ryan, Jason T.; Gundlach, David; Cheung, Kin. P., E-mail: Kin.Cheung@NIST.gov [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); Liu, Changze [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); Institute of Microelectronics, Peking University, Beijing 100871 (China); Southwick, Richard G. [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); IBM Research, Albany, NY 12205 (United States); Oates, Anthony S. [Taiwan Semiconductor Manufacturing Corporation, Hsinchu 30844, Taiwan (China); Huang, Ru [Institute of Microelectronics, Peking University, Beijing 100871 (China)

    2016-06-15

    Wave scattering by a potential step is a ubiquitous concept. Thus, it is surprising that theoretical treatments of ballistic transport in nanoscale devices, from quantum point contacts to ballistic transistors, assume no reflection even when the potential step is encountered upon exiting the device. Experiments so far seem to support this even if it is not clear why. Here we report clear evidence of coherent reflection when electron wave exits the channel of a nanoscale transistor and when the electron energy is low. The observed behavior is well described by a simple rectangular potential barrier model which the Schrodinger’s equation can be solved exactly. We can explain why reflection is not observed in most situations but cannot be ignored in some important situations. Our experiment also represents a direct measurement of electron injection velocity - a critical quantity in nanoscale transistors that is widely considered not measurable.

  18. Suprathermal Electron Generation and Channel Formation by an Ultrarelativistic Laser Pulse in an Underdense Preformed Plasma

    International Nuclear Information System (INIS)

    Malka, G.; Gaillard, R.; Miquel, J.L.; Rousseaux, C.; Bonnaud, G.; Busquet, M.; Lours, L.; Fuchs, J.; Pepin, H.; Fuchs, J.; Amiranoff, F.; Baton, S.D.

    1997-01-01

    Relativistic electrons are produced, with energies up to 20MeV, by the interaction of a high-intensity subpicosecond laser pulse (1 μm , 300 fs , 10 19 W/cm 2 ) with an underdense plasma. Two suprathermal electron populations appear with temperatures of 1 and 3MeV. In the same conditions, the laser beam transmission is increased up to 20% 30%. We observe both features along with the evidence of laser pulse channeling. A fluid model predicts a strong self-focusing of the pulse. Acceleration in the enhanced laser field seems the most likely mechanism leading to the second electron population. copyright 1997 The American Physical Society

  19. Cryo-electron microscopy structure of the lysosomal calcium-permeable channel TRPML3.

    Science.gov (United States)

    Hirschi, Marscha; Herzik, Mark A; Wie, Jinhong; Suo, Yang; Borschel, William F; Ren, Dejian; Lander, Gabriel C; Lee, Seok-Yong

    2017-10-19

    The modulation of ion channel activity by lipids is increasingly recognized as a fundamental component of cellular signalling. The transient receptor potential mucolipin (TRPML) channel family belongs to the TRP superfamily and is composed of three members: TRPML1-TRPML3. TRPMLs are the major Ca 2+ -permeable channels on late endosomes and lysosomes (LEL). They regulate the release of Ca 2+ from organelles, which is important for various physiological processes, including organelle trafficking and fusion. Loss-of-function mutations in the MCOLN1 gene, which encodes TRPML1, cause the neurodegenerative lysosomal storage disorder mucolipidosis type IV, and a gain-of-function mutation (Ala419Pro) in TRPML3 gives rise to the varitint-waddler (Va) mouse phenotype. Notably, TRPML channels are activated by the low-abundance and LEL-enriched signalling lipid phosphatidylinositol-3,5-bisphosphate (PtdIns(3,5)P 2 ), whereas other phosphoinositides such as PtdIns(4,5)P 2 , which is enriched in plasma membranes, inhibit TRPMLs. Conserved basic residues at the N terminus of the channel are important for activation by PtdIns(3,5)P 2 and inhibition by PtdIns(4,5)P 2 . However, owing to a lack of structural information, the mechanism by which TRPML channels recognize PtdIns(3,5)P 2 and increase their Ca 2+ conductance remains unclear. Here we present the cryo-electron microscopy (cryo-EM) structure of a full-length TRPML3 channel from the common marmoset (Callithrix jacchus) at an overall resolution of 2.9 Å. Our structure reveals not only the molecular basis of ion conduction but also the unique architecture of TRPMLs, wherein the voltage sensor-like domain is linked to the pore via a cytosolic domain that we term the mucolipin domain. Combined with functional studies, these data suggest that the mucolipin domain is responsible for PtdIns(3,5)P 2 binding and subsequent channel activation, and that it acts as a 'gating pulley' for lipid-dependent TRPML gating.

  20. Channeling and Radiation of Electrons in Silicon Single Crystals and Si1−xGex Crystalline Undulators

    DEFF Research Database (Denmark)

    Backe, H.; Krambrich, D.; Lauth, W.

    2013-01-01

    The phenomenon of channeling and the basic features of channeling radiation emission are introduced in a pedestrian way. Both, radiation spectra as well as dechanneling length measurements at electron beam energies between 195 and 855 MeV feature quantum state phenomena for the (110) planar...

  1. Principal parameters of classical multiply charged ion sources

    International Nuclear Information System (INIS)

    Winter, H.; Wolf, B.H.

    1974-01-01

    A review is given of the operational principles of classical multiply charged ion sources (operating sources for intense beams of multiply charged ions using discharge plasmas; MCIS). The fractional rates of creation of multiply charged ions in MCIS plasmas cannot be deduced from the discharge parameters in a simple manner; they depend essentially on three principal parameters, the density and energy distribution of the ionizing electrons, and the confinement time of ions in the ionization space. Simple discharge models were used to find relations between principal parameters, and results of model calculations are compared to actually measured charge state density distributions of extracted ions. Details of processes which determine the energy distribution of ionizing electrons (heating effects), confinement times of ions (instabilities), and some technical aspects of classical MCIS (cathodes, surface processes, conditioning, life time) are discussed

  2. Flow visualization and velocity measurement in a small-scale open channel using an electron microscope

    International Nuclear Information System (INIS)

    Yasuda, K; Sogo, M; Iwamoto, Y

    2013-01-01

    The present note describes a method for use in conjunction with a scanning electron microscope (SEM) that has been developed to visualize a liquid flow under a high-level vacuum and to measure a velocity field in a small-scale flow through an open channel. In general, liquid cannot be observed via a SEM, because liquid evaporates under the high-vacuum environment of the SEM. As such, ionic liquid and room temperature molten salt having a vapor pressure of nearly zero is used in the present study. We use ionic liquid containing Au-coated tracer particles to visualize a small-scale flow under a SEM. Furthermore, the velocity distribution in the open channel is obtained by particle tracking velocimetry measurement and a parabolic profile is confirmed. (technical design note)

  3. Determination of microturbulence enhanced electron collisionality in magnetized coaxial accelerator channels by direct magnetic field measurement

    International Nuclear Information System (INIS)

    Black, D.C.; Mayo, R.M.; Caress, R.W.

    1997-01-01

    A miniature magnetic probe array, consisting of 10 spatially separated coils, has been used to obtain profile information on the time varying magnetic field within the 2.54 cm wide flow channel of the coaxial plasma source experiment (CPS-1) [R. M. Mayo et al., Plasma Sources Sci. Technol. 4, 47 (1995)]. The magnetic field data have been used, together with a resistive, Hall magnetohydrodynamic (MHD) model of applied field distortion by the flowing plasma, to obtain estimates of the microturbulent enhancement to electron collisionality within the CPS-1 flow channel. These measurements provide direct experimental evidence of anomalous electron collisionality, a previously predicted effect in these devices. The anomaly parameter, a=ν an /ν cl , determined both from the distortion of contours of constant magnetic flux, and from local B θ and B z measurements scales with the classical electron magnetization parameter (Ω cl =ω ce /ν e cl ), indicating that collisionality plays a strong role in determining the level of anomalous transport in the plasma. When this anomaly parameter scaling is cast in terms of the ratio ν e cl /ω lh , it is found that the resistivity enhancement scales with ν e cl /ω lh , and becomes significant at ν e cl /ω lh ≤1, suggesting that a lower hybrid drift instability may be the responsible mechanism for enhanced transport. copyright 1997 American Institute of Physics

  4. Study of the structure of the particles of channel black of phase-contrasting electron microscopy of high resolution

    Energy Technology Data Exchange (ETDEWEB)

    Varlakov, V.P.; Fialkov, A.S.; Smirnov, B.N.

    1981-01-01

    The structure of channel black, DG-100, in the initial and graphitized states has been studied by phase-contrasting electron microscopy with a direct resolution of the carbon layers. An individual carbon layer is the main structural element of carbon black. The structure of channel black in the graphitized state looks like a hollow closed polyhedron made up of bundles of continuous carbon layers which can bend and become deformed to a great extent, testifying to the polymeric nature of the structure of channel black. The authors give an interpretation of the roentgen values of the 'dimensions of crystallites' in channel black.

  5. Characteristics of four-channel Cherenkov-type detector for measurements of runaway electrons in the ISTTOK tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Plyusnin, V. V.; Duarte, P.; Fernandes, H.; Silva, C. [Instituto de Plasmas e FuSao Nuclear - Laboratorio Associado, Association Euratom/IST, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Jakubowski, L.; Zebrowski, J.; Malinowski, K.; Rabinski, M.; Sadowski, M. J. [The Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland)

    2010-10-15

    A diagnostics capable of characterizing the runaway and superthermal electrons has been developing on the ISTTOK tokamak. In previous paper, a use of single-channel Cherenkov-type detector with titanium filter for runaway electron studies in ISTTOK was reported. To measure fast electron populations with different energies, a prototype of a four-channel detector with molybdenum filters was designed. Test-stand studies of filters with different thicknesses (1, 3, 7, 10, 20, 50, and 100 {mu}m) have shown that they should allow the detection of electrons with energies higher than 69, 75, 87, 95, 120, 181, and 260 keV, respectively. First results of measurements with the four-channel detector revealed the possibility to measure reliably different fast electrons populations simultaneously.

  6. Hot LO-phonon limited electron transport in ZnO/MgZnO channels

    Science.gov (United States)

    Šermukšnis, E.; Liberis, J.; Matulionis, A.; Avrutin, V.; Toporkov, M.; Özgür, Ü.; Morkoç, H.

    2018-05-01

    High-field electron transport in two-dimensional channels at ZnO/MgZnO heterointerfaces has been investigated experimentally. Pulsed current-voltage (I-V) and microwave noise measurements used voltage pulse widths down to 30 ns and electric fields up to 100 kV/cm. The samples investigated featured electron densities in the range of 4.2-6.5 × 1012 cm-2, and room temperature mobilities of 142-185 cm2/V s. The pulsed nature of the applied field ensured negligible, if any, change in the electron density, thereby allowing velocity extraction from current with confidence. The highest extracted electron drift velocity of ˜0.5 × 107 cm/s is somewhat smaller than that estimated for bulk ZnO; this difference is explained in the framework of longitudinal optical phonon accumulation (hot-phonon effect). The microwave noise data allowed us to rule out the effect of excess acoustic phonon temperature caused by Joule heating. Real-space transfer of hot electrons into the wider bandgap MgZnO layer was observed to be a limiting factor in samples with a high Mg content (48%), due to phase segregation and the associated local lowering of the potential barrier.

  7. Electron transfer activation of a second water channel for proton transport in [FeFe]-hydrogenase

    Energy Technology Data Exchange (ETDEWEB)

    Sode, Olaseni; Voth, Gregory A., E-mail: gavoth@uchicago.edu [Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, Computation Institute, The University of Chicago, Chicago, Illinois 60637, USA and Computing, Environment and Life Sciences, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2014-12-14

    Hydrogenase enzymes are important because they can reversibly catalyze the production of molecular hydrogen. Proton transport mechanisms have been previously studied in residue pathways that lead to the active site of the enzyme via residues Cys299 and Ser319. The importance of this pathway and these residues has been previously exhibited through site-specific mutations, which were shown to interrupt the enzyme activity. It has been shown recently that a separate water channel (WC2) is coupled with electron transport to the active site of the [FeFe]-hydrogenase. The water-mediated proton transport mechanisms of the enzyme in different electronic states have been studied using the multistate empirical valence bond reactive molecular dynamics method, in order to understand any role WC2 may have in facilitating the residue pathway in bringing an additional proton to the enzyme active site. In a single electronic state A{sup 2−}, a water wire was formed through which protons can be transported with a low free energy barrier. The remaining electronic states were shown, however, to be highly unfavorable to proton transport in WC2. A double amino acid substitution is predicted to obstruct proton transport in electronic state A{sup 2-} by closing a cavity that could otherwise fill with water near the proximal Fe of the active site.

  8. Electron transfer activation of a second water channel for proton transport in [FeFe]-hydrogenase

    International Nuclear Information System (INIS)

    Sode, Olaseni; Voth, Gregory A.

    2014-01-01

    Hydrogenase enzymes are important because they can reversibly catalyze the production of molecular hydrogen. Proton transport mechanisms have been previously studied in residue pathways that lead to the active site of the enzyme via residues Cys299 and Ser319. The importance of this pathway and these residues has been previously exhibited through site-specific mutations, which were shown to interrupt the enzyme activity. It has been shown recently that a separate water channel (WC2) is coupled with electron transport to the active site of the [FeFe]-hydrogenase. The water-mediated proton transport mechanisms of the enzyme in different electronic states have been studied using the multistate empirical valence bond reactive molecular dynamics method, in order to understand any role WC2 may have in facilitating the residue pathway in bringing an additional proton to the enzyme active site. In a single electronic state A 2− , a water wire was formed through which protons can be transported with a low free energy barrier. The remaining electronic states were shown, however, to be highly unfavorable to proton transport in WC2. A double amino acid substitution is predicted to obstruct proton transport in electronic state A 2- by closing a cavity that could otherwise fill with water near the proximal Fe of the active site

  9. 0.56 GeV laser electron acceleration in ablative-capillary-discharge plasma channel

    International Nuclear Information System (INIS)

    Kameshima, Takashi; Kurokawa, Shin-ichi; Nakajima, Kazuhisa; Hong Wei; Wen Xianlun; Wu Yuchi; Tang Chuanming; Zhu Qihua; Gu Yuqiu; Zhang Baohan; Peng Hansheng; Sugiyama, Kiyohiro; Chen, Liming; Tajima, Toshiki; Kumita, Tetsuro

    2008-01-01

    A high-quality electron beam with a central energy of 0.56 GeV, an energy spread of 1.2% rms, and a divergence of 0.59 mrad rms was produced by means of a 4 cm ablative-capillary-discharge plasma channel driven by a 3.8 J27 fs laser pulse. This is the first demonstration of electron acceleration with an ablative capillary discharge wherein the capillary is stably operated in vacuum with a simple system triggered by a laser pulse. This result of the generation of a high-quality beam provides the prospects to realize a practical accelerator based on laser-plasma acceleration. (author)

  10. Ultra-short channel GaN high electron mobility transistor-like Gunn diode with composite contact

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ying; Yang, Lin' an, E-mail: layang@xidian.edu.cn; Wang, Zhizhe; Chen, Qing; Huang, Yonghong; Dai, Yang; Chen, Haoran; Zhao, Hongliang; Hao, Yue [The State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi' an 710071 (China)

    2014-09-07

    We present a numerical analysis on an ultra-short channel AlGaN/GaN HEMT-like planar Gunn diode based on the velocity-field dependence of two-dimensional electron gas (2-DEG) channel accounting for the ballistic electron acceleration and the inter-valley transfer. In particular, we propose a Schottky-ohmic composite contact instead of traditional ohmic contact for the Gunn diode in order to significantly suppress the impact ionization at the anode side and shorten the “dead zone” at the cathode side, which is beneficial to the formation and propagation of dipole domain in the ultra-short 2-DEG channel and the promotion of conversion efficiency. The influence of the surface donor-like traps on the electron domain in the 2-DEG channel is also included in the simulation.

  11. A Mathematica package for calculation of planar channeling radiation spectra of relativistic electrons channeled in a diamond-structure single crystal (quantum approach)

    Science.gov (United States)

    Azadegan, B.

    2013-03-01

    The presented Mathematica code is an efficient tool for simulation of planar channeling radiation spectra of relativistic electrons channeled along major crystallographic planes of a diamond-structure single crystal. The program is based on the quantum theory of channeling radiation which has been successfully applied to study planar channeling at electron energies between 10 and 100 MeV. Continuum potentials for different planes of diamond, silicon and germanium single crystals are calculated using the Doyle-Turner approximation to the atomic scattering factor and taking thermal vibrations of the crystal atoms into account. Numerical methods are applied to solve the one-dimensional Schrödinger equation. The code is designed to calculate the electron wave functions, transverse electron states in the planar continuum potential, transition energies, line widths of channeling radiation and depth dependencies of the population of quantum states. Finally the spectral distribution of spontaneously emitted channeling radiation is obtained. The simulation of radiation spectra considerably facilitates the interpretation of experimental data. Catalog identifier: AEOH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 446 No. of bytes in distributed program, including test data, etc.: 209805 Distribution format: tar.gz Programming language: Mathematica. Computer: Platforms on which Mathematica is available. Operating system: Operating systems on which Mathematica is available. RAM: 1 MB Classification: 7.10. Nature of problem: Planar channeling radiation is emitted by relativistic charged particles during traversing a single crystal in direction parallel to a crystallographic plane. Channeling is modeled as the motion

  12. Electronic Communication Channel Use and Health Information Source Preferences Among Latinos in Northern Manhattan.

    Science.gov (United States)

    Hillyer, Grace Clarke; Schmitt, Karen M; Lizardo, Maria; Reyes, Andria; Bazan, Mercedes; Alvarez, Maria C; Sandoval, Rossy; Abdul, Kazeem; Orjuela, Manuela A

    2017-04-01

    Understanding key health concepts is crucial to participation in Precision Medicine initiatives. In order to assess methods to develop and disseminate a curriculum to educate community members in Northern Manhattan about Precision Medicine, clients from a local community-based organization were interviewed during 2014-2015. Health literacy, acculturation, use of Internet, email, and text messaging, and health information sources were assessed. Associations between age and outcomes were evaluated; multivariable analysis used to examine the relationship between participant characteristics and sources of health information. Of 497 interviewed, 29.4 % had inadequate health literacy and 53.6 % had access to the Internet, 43.9 % to email, and 45.3 % to text messaging. Having adequate health literacy was associated with seeking information from a healthcare professional (OR 2.59, 95 % CI 1.54-4.35) and from the Internet (OR 3.15, 95 % CI 1.97-5.04); having ≤ grade school education (OR 2.61, 95 % CI 1.32-5.17) also preferred information from their provider; persons >45 years (OR 0.29, 95 % CI 0.18-0.47) were less likely to use the Internet for health information and preferred printed media (OR 1.64, 95 % CI 1.07-2.50). Overall, electronic communication channel use was low and varied significantly by age with those ≤45 years more likely to utilize electronic channels. Preferred sources of health information also varied by age as well as by health literacy and educational level. This study demonstrates that to effectively communicate key Precision Medicine concepts, curriculum development for Latino community members of Northern Manhattan will require attention to health literacy, language preference and acculturation and incorporate more traditional communication channels for older community members.

  13. New channeling effects in the radiative emission of 150 GeV electrons in a thin germanium crystal

    International Nuclear Information System (INIS)

    Belkacem, A.; Chevallier, M.; Gaillard, M.J.; Genre, R.; Kirsch, R.; Poizat, J.C.; Remillieux, J.; Bologna, G.; Peigneux, J.P.; Sillou, D.; Spighel, M.; Cue, N.; Kimball, J.C.; Marsh, B.; Sun, C.R.

    1986-01-01

    The orientation dependence of the radiative emission of 150 GeV electrons and positrons incident at small angles with respect to the axial direction of a thin (0.185 mm) Ge crystal has been observed. The processes are well understood, except for channeled electrons, which radiate unexpected high energy photons. (orig.)

  14. Quantum–classical simulations of the electronic stopping force and charge on slow heavy channelling ions in metals

    International Nuclear Information System (INIS)

    Race, C P; Mason, D R; Foo, M H F; Foulkes, W M C; Sutton, A P; Horsfield, A P

    2013-01-01

    By simulating the passage of heavy ions along open channels in a model crystalline metal using semi-classical Ehrenfest dynamics we directly investigate the nature of non-adiabatic electronic effects. Our time-dependent tight-binding approach incorporates both an explicit quantum mechanical electronic system and an explicit representation of a set of classical ions. The coupled evolution of the ions and electrons allows us to explore phenomena that lie beyond the approximations made in classical molecular dynamics simulations and in theories of electronic stopping. We report a velocity-dependent charge-localization phenomenon not predicted by previous theoretical treatments of channelling. This charge localization can be attributed to the excitation of electrons into defect states highly localized on the channelling ion. These modes of excitation only become active when the frequency at which the channelling ion moves from interstitial point to equivalent interstitial point matches the frequency corresponding to excitations from the Fermi level into the localized states. Examining the stopping force exerted on the channelling ion by the electronic system, we find broad agreement with theories of slow ion stopping (a stopping force proportional to velocity) for a low velocity channelling ion (up to about 0.5 nm fs −1 from our calculations), and a reduction in stopping power attributable to the charge localization effect at higher velocities. By exploiting the simplicity of our electronic structure model we are able to illuminate the physics behind the excitation processes that we observe and present an intuitive picture of electronic stopping from a real-space, chemical perspective. (paper)

  15. Chemical Selectivity and Sensitivity of a 16-Channel Electronic Nose for Trace Vapour Detection

    Directory of Open Access Journals (Sweden)

    Drago Strle

    2017-12-01

    Full Text Available Good chemical selectivity of sensors for detecting vapour traces of targeted molecules is vital to reliable detection systems for explosives and other harmful materials. We present the design, construction and measurements of the electronic response of a 16 channel electronic nose based on 16 differential microcapacitors, which were surface-functionalized by different silanes. The e-nose detects less than 1 molecule of TNT out of 10+12 N2 molecules in a carrier gas in 1 s. Differently silanized sensors give different responses to different molecules. Electronic responses are presented for TNT, RDX, DNT, H2S, HCN, FeS, NH3, propane, methanol, acetone, ethanol, methane, toluene and water. We consider the number density of these molecules and find that silane surfaces show extreme affinity for attracting molecules of TNT, DNT and RDX. The probability to bind these molecules and form a surface-adsorbate is typically 10+7 times larger than the probability to bind water molecules, for example. We present a matrix of responses of differently functionalized microcapacitors and we propose that chemical selectivity of multichannel e-nose could be enhanced by using artificial intelligence deep learning methods.

  16. Hypoxic augmentation of Ca2+ channel currents requires a functional electron transport chain.

    Science.gov (United States)

    Brown, Stephen T; Scragg, Jason L; Boyle, John P; Hudasek, Kristin; Peers, Chris; Fearon, Ian M

    2005-06-10

    The incidence of Alzheimer disease is increased following ischemic episodes, and we previously demonstrated that following chronic hypoxia (CH), amyloid beta (Abeta) peptide-mediated increases in voltage-gated L-type Ca(2+) channel activity contribute to the Ca(2+) dyshomeostasis seen in Alzheimer disease. Because in certain cell types mitochondria are responsible for detecting altered O(2) levels we examined the role of mitochondrial oxidant production in the regulation of recombinant Ca(2+) channel alpha(1C) subunits during CH and exposure to Abeta-(1-40). In wild-type (rho(+)) HEK 293 cells expressing recombinant L-type alpha(1C) subunits, Ca(2+) currents were enhanced by prolonged (24 h) exposure to either CH (6% O(2)) or Abeta-(1-40) (50 nm). By contrast the response to CH was absent in rho(0) cells in which the mitochondrial electron transport chain (ETC) was depleted following long term treatment with ethidium bromide or in rho(+) cells cultured in the presence of 1 microm rotenone. CH was mimicked in rho(0) cells by the exogenous production of O2(-.). by xanthine/xanthine oxidase. Furthermore Abeta-(1-40) enhanced currents in rho(0) cells to a degree similar to that seen in cells with an intact ETC. The antioxidants ascorbate (200 microm) and Trolox (500 microm) ablated the effect of CH in rho(+) cells but were without effect on Abeta-(1-40)-mediated augmentation of Ca(2+) current in rho(0) cells. Thus oxidant production in the mitochondrial ETC is a critical factor, acting upstream of amyloid beta peptide production in the up-regulation of Ca(2+) channels in response to CH.

  17. Scale up and application of equal-channel angular extrusion for the electronics and aerospace industries

    International Nuclear Information System (INIS)

    Ferrasse, Stephane; Segal, V.M.; Alford, Frank; Kardokus, Janine; Strothers, Susan

    2008-01-01

    Two areas are critical to promote equal-channel angular extrusion beyond the stage of a laboratory curiosity: (i) tool/processing design and scale up; (ii) development of new submicrometer-grained products. Both goals are pursued at Honeywell. The first case is the successful commercialization of ECAE for the production of sputtering targets from single phase alloys in the electronic industry. Blank dimensions are significantly larger than those reported in the literature. Other described applications are targeted to the increase of tensile strength, high-cycle fatigue and toughness in medium-to-heavily alloyed Al materials used in aerospace. In these alloys, the optimal properties can be reached with better understanding of the interplay between plastic deformation and precipitation mechanisms

  18. Self-fields in free-electron lasers with planar wiggler and ion-channel guiding

    International Nuclear Information System (INIS)

    Farokhi, B; Jafary, F B; Maraghechi, B

    2006-01-01

    A theory of self-electric and self-magnetic fields of a relativistic electron beam passing through a one-dimensional planar wiggler and an ion-channel is presented. The equilibrium orbits and their stability, under the influence of self-electric and self-magnetic fields, are analysed. New unstable orbits, in the first part of the group I orbits, are found. It is shown that for a low energy and high density beam the self-fields can produce very large effects. Stabilities of quasi-steady-state orbits are investigated by analytical and numerical methods and perfect agreement was found. The theory of small signal gain is used to derive a formula for the gain with the self-field effects included. A numerical analysis is conducted to study the self-field effects on the quasi-steady-state orbits and the gain

  19. Development of a multi-channel front-end electronics module based on ASIC for silicon strip array detectors

    International Nuclear Information System (INIS)

    Zhao Xingwen; Yan Duo; Su Hong; Qian Yi; Kong Jie; Zhang Xueheng; Li Zhankui; Li Haixia

    2014-01-01

    The silicon strip array detector is one of external target facility subsystems in the Cooling Storage Ring on the Heavy Ion Research Facility at Lanzhou (HIRFL-CSR). Using the ASICs, the front-end electronics module has been developed for the silicon strip array detectors and can implement measurement of energy of 96 channels. The performance of the front-end electronics module has been tested. The energy linearity of the front-end electronics module is better than 0.3% for the dynamic range of 0.1∼0.7 V. The energy resolution is better than 0.45%. The maximum channel crosstalk is better than 10%. The channel consistency is better than 1.3%. After continuously working for 24 h at room temperature, the maximum drift of the zero-peak is 1.48 mV. (authors)

  20. Selective Dirac voltage engineering of individual graphene field-effect transistors for digital inverter and frequency multiplier integrations.

    Science.gov (United States)

    Sul, Onejae; Kim, Kyumin; Jung, Yungwoo; Choi, Eunsuk; Lee, Seung-Beck

    2017-09-15

    The ambipolar band structure of graphene presents unique opportunities for novel electronic device applications. A cycle of gate voltage sweep in a conventional graphene transistor produces a frequency-doubled output current. To increase the frequency further, we used various graphene doping control techniques to produce Dirac voltage engineered graphene channels. The various surface treatments and substrate conditions produced differently doped graphene channels that were integrated on a single substrate and multiple Dirac voltages were observed by applying a single gate voltage sweep. We applied the Dirac voltage engineering techniques to graphene field-effect transistors on a single chip for the fabrication of a frequency multiplier and a logic inverter demonstrating analog and digital circuit application possibilities.

  1. Selective Dirac voltage engineering of individual graphene field-effect transistors for digital inverter and frequency multiplier integrations

    Science.gov (United States)

    Sul, Onejae; Kim, Kyumin; Jung, Yungwoo; Choi, Eunsuk; Lee, Seung-Beck

    2017-09-01

    The ambipolar band structure of graphene presents unique opportunities for novel electronic device applications. A cycle of gate voltage sweep in a conventional graphene transistor produces a frequency-doubled output current. To increase the frequency further, we used various graphene doping control techniques to produce Dirac voltage engineered graphene channels. The various surface treatments and substrate conditions produced differently doped graphene channels that were integrated on a single substrate and multiple Dirac voltages were observed by applying a single gate voltage sweep. We applied the Dirac voltage engineering techniques to graphene field-effect transistors on a single chip for the fabrication of a frequency multiplier and a logic inverter demonstrating analog and digital circuit application possibilities.

  2. Synthesis algorithm of VLSI multipliers for ASIC

    Science.gov (United States)

    Chua, O. H.; Eldin, A. G.

    1993-01-01

    Multipliers are critical sub-blocks in ASIC design, especially for digital signal processing and communications applications. A flexible multiplier synthesis tool is developed which is capable of generating multiplier blocks for word size in the range of 4 to 256 bits. A comparison of existing multiplier algorithms is made in terms of speed, silicon area, and suitability for automated synthesis and verification of its VLSI implementation. The algorithm divides the range of supported word sizes into sub-ranges and provides each sub-range with a specific multiplier architecture for optimal speed and area. The algorithm of the synthesis tool and the multiplier architectures are presented. Circuit implementation and the automated synthesis methodology are discussed.

  3. Generation of a pulsed low-energy electron beam using the channel spark device

    Energy Technology Data Exchange (ETDEWEB)

    Elgarhy, M. A. I., E-mail: elgarhy@azhar.edu.eg; Hassaballa, S. E.; Rashed, U. M.; ElSabbagh, M. M.; Saudy, A. H. [Physics Department, Faculty of Science, Al-Azhar University, Cairo (Egypt); Soliman, H. M. [Plasma and Nuclear Fusion Department, Atomic Energy Authority, Enshas (Egypt)

    2015-12-15

    For the generation of low-energy electron beam, the design and characteristics of channel spark discharge (CSD) operating at a low voltage are presented in this paper. The discharge voltage, discharge current, X-ray emissions, and electron beam current were experimentally determined. The effects of the applied voltage, working gas pressure, and external capacitance on the CSD and beam parameters were measured. At an applied voltage of 11 kV, an oxygen gas pressure of 25 mTorr, and an external capacitance of 16.45 nF, the maximum measured current was 900 A. The discharge current increased with the increase in the pressure and capacitance, while its periodic time decreased with the increase in the pressure. Two types of the discharge were identified and recorded: the hollow cathode discharge and the conduction discharge. A Faraday cup was used to measure the beam current. The maximum measured beam current was 120 A, and the beam signal exhibited two peaks. The increase in both the external capacitance and the applied discharge voltage increased the maximum electron beam current. The electron-beam pulse time decreased with the increase in the gas pressure at a constant voltage and increased with the decrease in the applied discharge voltage. At an applied voltage of 11 kV and an oxygen gas pressure of 15 mTorr, the maximum beam energy was 2.8 keV. The X-ray signal intensity decreased with the increase in the gas pressure and increased with the increase in the capacitance.

  4. Free-electron laser with a plasma wave wiggler propagating through a magnetized plasma channel

    International Nuclear Information System (INIS)

    Jafari, S; Jafarinia, F; Mehdian, H

    2013-01-01

    A plasma eigenmode has been employed as a wiggler in a magnetized plasma channel for the generation of laser radiation in a free-electron laser. The short wavelength of the plasma wave allows a higher radiation frequency to be obtained than from conventional wiggler free-electron lasers. The plasma can significantly slow down the radiation mode, thereby relaxing the beam energy requirement considerably. In addition, it allows a beam current in excess of the vacuum current limit via charge neutralization. This configuration has a higher tunability by controlling the plasma density in addition to the γ-tunability of the standard FEL. The laser gain has been calculated and numerical computations of the electron trajectories and gain are presented. Four groups (I–IV) of electron orbits have been found. It has been shown that by increasing the cyclotron frequency, the gain for orbits of group I and group III increases, while a decrease in gain has been obtained for orbits of group II and group IV. Similarly, the effect of plasma density on gain has been exhibited. The results indicate that with increasing plasma density, the orbits of all groups shift to higher cyclotron frequencies. The effects of beam self-fields on gain have also been demonstrated. It has been found that in the presence of beam self-fields the sensitivity of the gain increases substantially in the vicinity of gyroresonance. Here, the gain enhancement and reduction are due to the paramagnetic and diamagnetic effects of the self-magnetic field, respectively. (paper)

  5. Focusing peculiarities of ion-channel guiding on a relativistic electron beam in a free-electron laser with a three-dimensional wiggler

    International Nuclear Information System (INIS)

    Ouyang, Zhengbiao; Zhang, Shi-Chang

    2014-01-01

    In a free-electron laser the ‘natural focusing’ effect of a three-dimensional wiggler is too weak to confine the transport of a relativistic electron beam when the beam has a high current and consequently an external focusing system is often needed. In this paper we study the focusing peculiarities of an ion-channel guide field on an electron beam. Nonlinear simulations of an electron beam transport show that, compared to an axial guide magnetic field, the ion-channel guide field results in smaller velocity–space and configuration–space spreads. The intrinsic mechanism of this physical phenomenon is that the ion-channel guide field confines the trajectory of the electron motion resulting in a smaller instantaneous curvature radius and a slighter curvature-center excursion than an axial guide magnetic field does. It is also found that, unlike with an axial guide magnetic field, over-focusing may occur if the ion-channel guide field is too strong. (paper)

  6. An electronic channel switching-based aptasensor for ultrasensitive protein detection

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongbo; Wang Cui [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Wu Zaisheng, E-mail: wuzaisheng@163.com [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Lu Limin; Qiu Liping; Zhou Hui; Shen Guoli [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Yu Ruqin, E-mail: rqyu@hnu.edu.cn [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2013-01-03

    Highlights: Black-Right-Pointing-Pointer Target IgE is successfully designed to serve as a barrier to separate enzyme from its substrate. Black-Right-Pointing-Pointer This sensing platform of electronic channel switching-based aptasensor can be simply manipulated. Black-Right-Pointing-Pointer The stable hairpin structure of anti-IgE aptamer is utilized to detect target IgE. Black-Right-Pointing-Pointer The sensor is ultrasensitive sensitivity, excellent selectivity and small volume of sample. Black-Right-Pointing-Pointer It is a powerful platform to be further expanded to detect more kinds of proteins and even cells. - Abstract: Due to the ubiquity and essential of the proteins in all living organisms, the identification and quantification of disease-specific proteins are particularly important. Because the conformational change of aptamer upon its target or probe/target/probe sandwich often is the primary prerequisite for the design of an electrochemical aptameric assay system, it is extremely difficult to construct the electrochemical aptasensor for protein assay because the corresponding aptamers cannot often meet the requirement. To circumvent the obstacles mentioned, an electronic channel switching-based (ECS) aptasensor for ultrasensitive protein detection is developed. The essential achievement made is that an innovative sensing concept is proposed: the hairpin structure of aptamer is designed to pull electroactive species toward electrode surface and makes the surface-immobilized IgE serve as a barrier that separates enzyme from its substrate. It seemingly ensures that the ECS aptasensor exhibits most excellent assay features, such as, a detection limit of 4.44 Multiplication-Sign 10{sup -6} {mu}g mL{sup -1} (22.7 fM, 220 zmol in 10-{mu}L sample) (demonstrating a 5 orders of magnitude improvement in detection sensitivity compared with classical electronic aptasensors) and dynamic response range from 4.44 Multiplication-Sign 10{sup -6} to 4.44 Multiplication

  7. Coherent bremsstrahlung and channeling radiation from electrons of one to three MeV in silicon and gold

    International Nuclear Information System (INIS)

    Watson, J.E.

    1981-01-01

    The observation of sharp peaks in the x-ray spectrum from 1 to 3 MeV electrons striking thin single crystals of silicon and gold is reported. These peaks were observed in the range 1 to 25 keV. The peaks are of two different origins, both direct results of the periodic nature of the target crystals. The first kind of radiation is caused by the interference of incoming and scattered electron wave functions. Because of the periodicity of the target material there is a coherence effect for certain bremsstrahlung wave vectors. This coherent bremsstrahlung, though well known at very high electron energies, has never been adequately studied at electron energies below several hundred MeV. Detailed agreement between theoretical prediction and observation in silicon is shown. The second kind of radiation is caused by electrons channeled along major crystal axes. The electrons enter certain quantized orbits as they channel and may emit photons as a consequence of transitions between the various orbits. Observations of channeling radiation for various crystal axes in silicon are presented. Both phenomena were observed in gold, the first such observation for any metallic target

  8. Otanps synapse linear relation multiplier circuit

    International Nuclear Information System (INIS)

    Chible, H.

    2008-01-01

    In this paper, a four quadrant VLSI analog multiplier will be proposed, in order to be used in the implementation of the neurons and synapses modules of the artificial neural networks. The main characteristics of this multiplier are the small silicon area and the low power consumption and the high value of the weight input voltage. (author)

  9. On compact multipliers of topological algebras

    International Nuclear Information System (INIS)

    Mohammad, N.

    1994-08-01

    It is shown that if the maximal ideal space Δ(A) of a semisimple commutative complete metrizable locally convex algebra contains no isolated points, then every compact multiplier is trivial. Particularly, compact multipliers on semisimple commutative Frechet algebras whose maximal ideal space has no isolated points are identically zero. (author). 5 refs

  10. Faster and Energy-Efficient Signed Multipliers

    Directory of Open Access Journals (Sweden)

    B. Ramkumar

    2013-01-01

    Full Text Available We demonstrate faster and energy-efficient column compression multiplication with very small area overheads by using a combination of two techniques: partition of the partial products into two parts for independent parallel column compression and acceleration of the final addition using new hybrid adder structures proposed here. Based on the proposed techniques, 8-b, 16-b, 32-b, and 64-b Wallace (W, Dadda (D, and HPM (H reduction tree based Baugh-Wooley multipliers are developed and compared with the regular W, D, H based Baugh-Wooley multipliers. The performances of the proposed multipliers are analyzed by evaluating the delay, area, and power, with 65 nm process technologies on interconnect and layout using industry standard design and layout tools. The result analysis shows that the 64-bit proposed multipliers are as much as 29%, 27%, and 21% faster than the regular W, D, H based Baugh-Wooley multipliers, respectively, with a maximum of only 2.4% power overhead. Also, the power-delay products (energy consumption of the proposed 16-b, 32-b, and 64-b multipliers are significantly lower than those of the regular Baugh-Wooley multiplier. Applicability of the proposed techniques to the Booth-Encoded multipliers is also discussed.

  11. Transformational Electronics: Towards Flexible Low-Cost High Mobility Channel Materials

    KAUST Repository

    Nassar, Joanna M.

    2014-05-01

    For the last four decades, Si CMOS technology has been advancing with Moore’s law prediction, working itself down to the sub-20 nm regime. However, fundamental problems and limitations arise with the down-scaling of transistors and thus new innovations needed to be discovered in order to further improve device performance without compromising power consumption and size. Thus, a lot of studies have focused on the development of new CMOS compatible architectures as well as the discovery of new high mobility channel materials that will allow further miniaturization of CMOS transistors and improvement of device performance. Pushing the limits even further, flexible and foldable electronics seem to be the new attractive topic. By being able to make our devices flexible through a CMOS compatible process, one will be able to integrate hundreds of billions of more transistors in a small volumetric space, allowing to increase the performance and speed of our electronics all together with making things thinner, lighter, smaller and even interactive with the human skin. Thus, in this thesis, we introduce for the first time a cost-effective CMOS compatible approach to make high-k/metal gate devices on flexible Germanium (Ge) and Silicon-Germanium (SiGe) platforms. In the first part, we will look at the various approaches in the literature that has been developed to get flexible platforms, as well as we will give a brief overview about epitaxial growth of Si1-xGex films. We will also examine the electrical properties of the Si1-xGex alloys up to Ge (x=1) and discuss how strain affects the band structure diagram, and thus the mobility of the material. We will also review the material growth properties as well as the state-of-the-art results on high mobility metal-oxide semiconductor capacitors (MOSCAPs) using strained SiGe films. Then, we will introduce the flexible process that we have developed, based on a cost-effective “trench-protect-release-reuse” approach, utilizing

  12. Temperature Insensitive Current-Mode Four Quadrant Multiplier Using Single CFCTA

    Directory of Open Access Journals (Sweden)

    Tuntrakool Sunti

    2017-01-01

    Full Text Available A four quadrant multiplier of two current input signals using active building block, namely current follower cascaded transconductance amplifier (CFCTA is presented in this paper. The proposed multiplier consists of only single CFCTA without the use of any passive element. The presented circuit has low impedance at current input node and high impedance at current output node which is convenient for cascading in current mode circuit without the need of current buffer circuits. The output current can multiply two input currents with temperature insensitivity. Moreover, the magnitude of output current can be controlled electronically via DC bias current. With only single active building block, the presented multiplier is suitable for integrated circuit implementation for analog signal processing. Simulation results from a PSpice program are presented in order to demonstrate the multiplier proposed here.

  13. Multiply-negatively charged aluminium clusters and fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, Noelle

    2008-07-15

    Multiply negatively charged aluminium clusters and fullerenes were generated in a Penning trap using the 'electron-bath' technique. Aluminium monoanions were generated using a laser vaporisation source. After this, two-, three- and four-times negatively charged aluminium clusters were generated for the first time. This research marks the first observation of tetra-anionic metal clusters in the gas phase. Additionally, doubly-negatively charged fullerenes were generated. The smallest fullerene dianion observed contained 70 atoms. (orig.)

  14. Enhanced mobility in vertically scaled N-polar high-electron-mobility transistors using GaN/InGaN composite channels

    Science.gov (United States)

    Li, Haoran; Wienecke, Steven; Romanczyk, Brian; Ahmadi, Elaheh; Guidry, Matthew; Zheng, Xun; Keller, Stacia; Mishra, Umesh K.

    2018-02-01

    A GaN/InGaN composite channel design for vertically scaled N-polar high-electron-mobility transistor (HEMT) structures is proposed and demonstrated by metal-organic chemical vapor deposition. In a conventional N-polar HEMT structure, as the channel thickness (tch) decreases, the sheet charge density (ns) decreases, the electric field in the channel increases, and the centroid of the two-dimensional electron gas (2DEG) moves towards the back-barrier/channel interface, resulting in stronger scattering and lower electron mobility (μ). In this study, a thin InGaN layer was introduced in-between the channel and the AlGaN cap to increase the 2DEG density and reduce the electric field in the channel and therefore increase the electron mobility. The dependence of μ on the InGaN thickness (tInGaN) and the indium composition (xIn) was investigated for different channel thicknesses. With optimized tInGaN and xIn, significant improvements in electron mobility were observed. For a 6 nm channel HEMT structure, the electron mobility increased from 606 to 1141 cm2/(V.s) when the 6 nm thick pure GaN channel was replaced by the 4 nm GaN/2 nm In0.1Ga0.9N composite channel.

  15. Quantum theory of scattering of channeled electrons and positrons in a crystal

    International Nuclear Information System (INIS)

    Bazylev, V.A.; Goloviznin, V.V.

    1982-01-01

    The quantum theory of elastic scattering of electrons and positrons on plane or axial channeling in a thin crystal is developed. The role of coherent (without phonon excitation) and incoherent scattering by atoms of the plane (chain) is investigated. It is shown that incoherent scattering which leads to dechanneling cannot be reduced to scattering by an isolated atom. Allowance for ordered arrangement of the atoms in the plane (chain) of the crystal leads to suppression of the motion levels. It is also shown that on movement of a particle along the plane in directions strongly differing from those of the principal axes, the scattering is incoherent and is determined by thermal vibrations of the nuclei. As the direction of the particle momentum approaches those of the principal axes, the role of coherent scattering without recoil by the crystal lattice nuclei increases and may become dicisive. The probability of large- angle scattering increases relatively in this case. Under certain conditions coherent scattering may become resonant [ru

  16. Study of unexplained hard photon production by electrons channelled in a crystal

    CERN Multimedia

    2002-01-01

    Our preceding experiment (NA33) designed to study the pair creation process in the interaction of high energy $\\gamma$ with a crystal in alignment conditions had revealed the existence of an unexpected peak in the radiation of 150 GeV e$^{-}$ beam for E$_{\\gamma}$/E$_{e^{-}} \\simeq$ 0.85 incident along the axis of a 185 $\\mu$m. Ge crystal and the photon multiplicity for the peak events has been measured to be M $\\simeq$ 5.7.\\\\ In NA42, in a 76 $\\mu$m crystal of the same crystallographic quality, the peak nearly disappears, and the photon multiplicity at x = 0.85 is only M $\\simeq$ 2.0. \\\\ The thickness dependence of the effect shows that the extrapolated multiplicity in the peak in a very thin crystal tends to unity. The high energy radiation peak emitted by axially channeled electrons in a thick crystal is then interpreted by the radiation cooling mechanism. \\\\ The extrapolation to zero thickness of these results will allow us to extract from the data the single $\\gamma$ radiation spectrum. The comparison o...

  17. Electron channeling X-ray microanalysis for cation configuration in irradiate magnesium alimate spinel

    International Nuclear Information System (INIS)

    Matsumura, S.; Soeda, T.; Zaluzec, N. J.; Kinoshita, C.

    1999-01-01

    High angular resolution electron channeling X-ray spectroscopy (HARECXS) was examined as a practical tool to locate lattice-ions in spinel crystals. The orientation dependent intensity distribution of emitted X-rays obtained by HARECXS is so sensitive to lattice-ion configuration in the illuminated areas that the occupation probabilities on specific positions in the crystal lattice can be determined accurately through comparison with the theoretical rocking curves. HARECXS measurements have revealed partially disordered cation arrangement in MgO·nAl 2 O 3 with n = 1.0 and 2.4. Most Al 3+ lattice-ions occupy the octahedral (VIII) sites, while Mg 2 lattice-ions reside on both the tetrahedral (IV) and the octahedral (VIII) sites. The structural vacancies are enriched in the IV-sites. Further evacuation of cations from the IV-sites to the VIII-sites is recognized in a disordering process induced by irradiation with 1 MeV Ne + ions up to 8.9 dpa at 870 K

  18. ANUSANSKAR: a 16 channel frontend electronics (FEE) ASIC targeted for silicon pixel array detector based prototype Alice FOCAL

    International Nuclear Information System (INIS)

    Mukhopadhyay, Sourav; Chandratre, V.B.; Sukhwani, Menka; Pithawa, C.K.; Singaraju, Ramnarayan; Muhuri, Sanjib; Nayak, T.; Khan, S.A.; Saini, Jogendra

    2013-01-01

    ANUSANSKAR is a 16 channel pulse processing ASIC with analog multiplexed output designed in 0.7 um standard CMOS technology with each channel consisting of CSA, Semi Gaussian pulse shaper, DC cancellation and pedestal control, track and hold, output buffer blocks. The ASIC's analog multiplexed output can be read serially in daisy-chain topology. Testing, characterization and validation of ANUSANSKAR ASIC as readout for prototype ALICE forward calorimeter (FOCAL) has been carried out in PS beam line at CERN with up to 6 GeV of pion and electron beam. This paper describes the ANUSANSKAR ASIC along with the experimental results. (author)

  19. Lane fuzzy collision in channel with potential deformation by photon-phonon-electron excitation and sub-atomic control

    International Nuclear Information System (INIS)

    Shen Jing

    1998-01-01

    Collision between μ + and the μ - beams in the crystal are forbidden due to the two beams having different ''lanes'' in a channel. A laser pulse of ps-fs shocks lattice kernel vibration and dilates lattice electron distribution. It deforms the Lindhard's potential which is then expressed in a quantized form as the Huang-Zhu's potential[1]. The dynamic lanes can be made to overlap in a channel to allow collision without ductile fracture. This raises a new technology of sub-atomic information and control, which has been raised by T. D. Lee

  20. Dispersion relation and growth in a two-stream free electron laser with helical wiggler and ion channel guiding

    International Nuclear Information System (INIS)

    Mehdian, Hassan; Abbasi, Negar

    2008-01-01

    A linear theory of two-stream free electron laser (FEL) with helical wiggler and ion channel guiding is presented. The dispersion relation is obtained with the help of fluid theory and the growth rate is analyzed through the numerical solutions. The considerable enhancement of the growth rate is demonstrated due to the two-stream instability and continuous tuning of peak growth rate ratio, two-stream FEL compared to single-stream FEL, in terms of varying the ion channel frequency is illustrated

  1. Performances of multi-channel ceramic photomultipliers

    International Nuclear Information System (INIS)

    Comby, G.; Karolak, M.; Piret, Y.; Mouly, J.P.

    1995-09-01

    Ceramic electron multipliers with real metal dynodes and independent channels ware constructed using multilayer ceramic technology. Tests of these prototypes show their capability to form sensitive detectors such as photomultipliers or light intensifiers. Here, we present results for the photocathode sensitivity, dynode activation, gain, linearity range and dynamic characteristics as well as the effect of 3-year aging of the main operational functions. The advantages provided by the ceramic components are discussed. These results motivate the development of a compact 256 pixel ceramic photomultiplier. (author)

  2. Keynesian multiplier versus velocity of money

    Science.gov (United States)

    Wang, Yougui; Xu, Yan; Liu, Li

    2010-08-01

    In this paper we present the relation between Keynesian multiplier and the velocity of money circulation in a money exchange model. For this purpose we modify the original exchange model by constructing the interrelation between income and expenditure. The random exchange yields an agent's income, which along with the amount of money he processed determines his expenditure. In this interactive process, both the circulation of money and Keynesian multiplier effect can be formulated. The equilibrium values of Keynesian multiplier are demonstrated to be closely related to the velocity of money. Thus the impacts of macroeconomic policies on aggregate income can be understood by concentrating solely on the variations of money circulation.

  3. Fragmentation study of isolated and nano-solvated biomolecules induced by collision with multiply charged ions and neutral particles

    International Nuclear Information System (INIS)

    Bernigaud, V.

    2009-01-01

    This thesis concerns a gas phase study of the fragmentation of bio-molecular systems induced by slow collisions with multiply charged ions (in the keV-region), alkali atoms and rare gases. The main objective was to study the physical processes involved in the dissociation of highly electronically excited systems. In order to elucidate the intrinsic properties of certain biomolecules (porphyrins and amino acids) we have performed experiments in the gas phase with isolated systems. The obtained results demonstrate the high stability of porphyrins after electron removal and attachment. Furthermore, a dependence of the fragmentation pattern produced by multiply charged ions on the isomeric structure of the alanine molecule has been shown. In a second part of the thesis, a strong influence of the environment of the biomolecule on the fragmentation channels, their modification and their new opening, has been clearly proven. This phenomenon occurs in the presence of other surrounding biomolecules (clusters of nucleobases) as well as for molecules of a solvent (molecules of water, methanol and acetonitrile) in which the biomolecule is embedded. In order to extend these studies to larger systems, a new experimental set-up, based on an electro-spray ion source combined with a quadrupole mass filter has been developed. Due to the successful tests and proposed improvements of the device future experiments will become available concerning the fragmentation of large charged and solvated bio-molecular systems induced by collision processes. (author) [fr

  4. Controlled generation of comb-like electron beams in plasma channels for polychromatic inverse Thomson γ-ray sources

    International Nuclear Information System (INIS)

    Kalmykov, S Y; Shadwick, B A; Davoine, X; Ghebregziabher, I; Lehe, R; Lifschitz, A F

    2016-01-01

    Propagating a relativistically intense, negatively chirped laser pulse (the bandwidth  >150 nm) in a plasma channel makes it possible to generate background-free, comb-like electron beams—sequences of synchronized bunches with a low phase-space volume and controlled energy spacing. The tail of the pulse, confined in the accelerator cavity (an electron density ‘bubble’), experiences periodic focusing, while the head, which is the most intense portion of the pulse, steadily self-guides. Oscillations of the cavity size cause periodic injection of electrons from the ambient plasma, creating an electron energy comb with the number of components, their mean energy, and energy spacing dependent on the channel radius and pulse length. These customizable electron beams enable the design of a tunable, all-optical source of pulsed, polychromatic γ-rays using the mechanism of inverse Thomson scattering, with up to  ∼10 −5 conversion efficiency from the drive pulse in the electron accelerator to the γ-ray beam. Such a source may radiate  ∼10 7 quasi-monochromatic photons per shot into a microsteradian-scale cone. The photon energy is distributed among several distinct bands, each having sub-30% energy spread, with a highest energy of 12.5 MeV. (paper)

  5. Production of high-quality electron bunches by dephasing and beam loading in channeled and unchanneled laser plasma accelerators

    International Nuclear Information System (INIS)

    Geddes, C.G.R.; Toth, Cs.; Tilborg, J. van; Esarey, E.; Schroeder, C.B.; Bruhwiler, D.; Nieter, C.; Cary, J.; Leemans, W.P.

    2005-01-01

    High-quality electron beams, with a few 10 9 electrons within a few percent of the same energy above 80 MeV, were produced in a laser wakefield accelerator by matching the acceleration length to the length over which electrons were accelerated and outran (dephased from) the wake. A plasma channel guided the drive laser over long distances, resulting in production of the high-energy, high-quality beams. Unchanneled experiments varying the length of the target plasma indicated that the high-quality bunches are produced near the dephasing length and demonstrated that channel guiding was more stable and efficient than relativistic self-guiding. Consistent with these data, particle-in-cell simulations indicate production of high-quality electron beams when trapping of an initial bunch of electrons suppresses further injection by loading the wake. The injected electron bunch is then compressed in energy by dephasing, when the front of the bunch begins to decelerate while the tail is still accelerated

  6. Multichannel marketing: an experiment on guiding citizens to the electronic channels

    NARCIS (Netherlands)

    Teerling, Marije L.; Pieterson, Willem Jan

    2010-01-01

    Governments have a variety of channels at their disposal to help them interact with their citizens. Having realized that citizens still prefer the traditional channels, governments are now focusing on ways to lead them to the web. Previously, we have shown that citizens prefer the use of soft

  7. Multipliers for continuous frames in Hilbert spaces

    International Nuclear Information System (INIS)

    Balazs, P; Bayer, D; Rahimi, A

    2012-01-01

    In this paper, we examine the general theory of continuous frame multipliers in Hilbert space. These operators are a generalization of the widely used notion of (discrete) frame multipliers. Well-known examples include anti-Wick operators, STFT multipliers or Calderón–Toeplitz operators. Due to the possible peculiarities of the underlying measure spaces, continuous frames do not behave quite as their discrete counterparts. Nonetheless, many results similar to the discrete case are proven for continuous frame multipliers as well, for instance compactness and Schatten-class properties. Furthermore, the concepts of controlled and weighted frames are transferred to the continuous setting. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’. (paper)

  8. Economic Multipliers and Mega-Event Analysis

    OpenAIRE

    Victor Matheson

    2004-01-01

    Critics of economic impact studies that purport to show that mega-events such as the Olympics bring large benefits to the communities “lucky” enough to host them frequently cite the use of inappropriate multipliers as a primary reason why these impact studies overstate the true economic gains to the hosts of these events. This brief paper shows in a numerical example how mega-events may lead to inflated multipliers and exaggerated claims of economic benefits.

  9. Nonlinear State of Sausage-like Instability of Electron Current Channels in Fast Ignition Concept of Inertial Fusion

    International Nuclear Information System (INIS)

    Jain, Neeraj; Das, Amita; Kaw, Predhiman; Sengupta, Sudip

    2003-01-01

    This paper deals with a detailed fluid simulation study of linear and nonlinear aspects of the velocity shear modes in electron current channels in a two dimensional geometry. Simulation results clearly show the flattening of flow profile and the development of sausage like structures (kink structures, which are intrinsically three dimensional excitations, are ruled out in the present simulations) which grow linearly and eventually saturate by nonlinear effects. An analytic understanding of the nonlinear saturation mechanism is also provided

  10. Electron impact ionization of B-like ion N2+. Resonance enhancement of the single-channel cross section

    International Nuclear Information System (INIS)

    Li Guohe; Qian Xingzhong; Pan Soufu

    1998-01-01

    The electron impact ionization cross sections of B-like ion N 2+ are calculated in the Coulomb-Born no exchange approximation by using R-matrix method, and the single differential cross section is given. The calculated results exhibit the Rydberg series of resonances. The resonance enhancement of the single-channel cross section is significantly greater than direct ionization cross section. It is agreement with that of Chidichimo

  11. A study of various types of electronics for drift chambers: development of a test bench and results for 1500 channels

    International Nuclear Information System (INIS)

    Kostarakis, Panayotis.

    1976-01-01

    An electronic chain to be connected with drift chambers is studied for use in High Energy Physics. Studies have been made to define the best components to be put into the elements (amplifiers, cables, TDC...). Measurements have been done to determine the characteristics of the chosen elements. A test apparatus has been built to control each channel (about 1550). Finally all chain elements have been tested [fr

  12. Charge-exchange collisions of multiply charged ions with atoms

    International Nuclear Information System (INIS)

    Grozdanov, T.P.; Janev, R.K.

    1978-01-01

    The problem of electron transfer between neutral atoms and multiply charged ions is considered at low and medium energies. It is assumed that a large number of final states are available for the electron transition so that the electron-capture process is treated as a tunnel effect caused by the strong attractive Coulomb field of the multicharged ions. The electron transition probability is obtained in a closed form using the modified-comparison-equation method to solve the Schroedinger equation. An approximately linear dependence of the one-electron transfer cross section on the charge of multicharged ion is found. Cross-section calculations of a number of charge-exchange reactions are performed

  13. Study of electron beams within ISTTOK tokamak by means of a multi-channel Cherenkov detector; their correlation with hard X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Jakubowski, L., E-mail: Lech.Jakubowski@ipj.gov.p [Andrzej Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland); Malinowski, K.; Sadowski, M.J.; Zebrowski, J. [Andrzej Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland); Plyusnin, V.V. [Association Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Rabinski, M. [Andrzej Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland); Fernandes, H.; Silva, C.; Duarte, P. [Association Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Jakubowski, M.J. [Andrzej Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland)

    2010-11-11

    The paper describes experimental studies of electron beams emitted from a plasma torus within the ISTTOK tokamak, which were performed by means of a new four-channel detector of the Cherenkov type. A range of electron energy was estimated. There were also measured hard X-rays, and their correlation with the fast run-away electron beams was investigated experimentally.

  14. Effects of self-fields on electron trajectory and gain in two-stream electromagnetically pumped free-electron laser with ion channel guiding

    International Nuclear Information System (INIS)

    Saviz, S.; Ghorannevis, M.; Aghamir, Farzin M.; Mehdian, H.

    2011-01-01

    A theory for the two-stream free-electron laser with an electromagnetic wiggler (EMW) and an ion channel guiding is developed. In the analysis, the effects of self-fields have been taken into account. The electron trajectories and the small signal gain are derived. The stability of the trajectories, the characteristics of the linear gain and the normalized maximum gain are studied numerically. The dependence of the normalized frequency ω-circumflex corresponding to the maximum gain on the ion-channel frequency is presented. The results show that there are seven groups of orbits in the presence of the self-fields, which are similar to those reported in the absence of the self-fields. It is also shown that the normalized gains of 2 groups decrease while the rest increase with the increasing normalized ion-channel frequency. Furthermore, it is found that the two-stream instability and the self-field lead to a decrease in the maximum gain except for group 4. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  15. Bio/Nano Electronic Devices and Sensors

    National Research Council Canada - National Science Library

    Jones, W. K

    2008-01-01

    ...) Cold cathode microwave generator and ceramic electron multiplier-ceramic multiplier using a novel secondary electron yield materials of MgO and CNT was demonstrated as well as cooling structures...

  16. Simulation of channeling and radiation of 855 MeV electrons and positrons in a small-amplitude short-period bent crystal

    Energy Technology Data Exchange (ETDEWEB)

    Korol, Andrei V., E-mail: korol@mbnexplorer.com [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); Bezchastnov, Victor G. [A.F. Ioffe Physical-Technical Institute, Politechnicheskaya Str. 26, 194021 St. Petersburg (Russian Federation); Peter the Great St. Petersburg Polytechnic University, Politechnicheskaya 29, 195251 St. Petersburg (Russian Federation); Sushko, Gennady B.; Solov’yov, Andrey V. [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany)

    2016-11-15

    Channeling and radiation are studied for the relativistic electrons and positrons passing through a Si crystal periodically bent with a small amplitude and a short period. Comprehensive analysis of the channeling process for various bending amplitudes is presented on the grounds of numerical simulations. The features of the channeling are highlighted and elucidated within an analytically developed continuous potential approximation. The radiation spectra are computed and discussed.

  17. Channeling, volume reflection, and volume capture study of electrons in a bent silicon crystal

    Directory of Open Access Journals (Sweden)

    T. N. Wistisen

    2016-07-01

    Full Text Available We present the experimental data and analysis of experiments conducted at SLAC National Accelerator Laboratory investigating the processes of channeling, volume-reflection and volume-capture along the (111 plane in a strongly bent quasimosaic silicon crystal. These phenomena were investigated at 5 energies: 3.35, 4.2, 6.3, 10.5, and 14.0 GeV with a crystal with bending radius of 0.15 m, corresponding to curvatures of 0.053, 0.066, 0.099, 0.16, and 0.22 times the critical curvature, respectively. Based on the parameters of fitting functions we have extracted important parameters describing the channeling process such as the dechanneling length, the angle of volume reflection, the surface transmission, and the widths of the distribution of channeled particles parallel and orthogonal to the plane.

  18. Inexpensive read-out for coincident electron spectroscopy with a transmission electron microscope at nanometer scale using micro channel plates and multistrip anodes

    International Nuclear Information System (INIS)

    Hollander, R.W.; Bom, V.R.; Van Eijk, C.W.E.; Faber, J.S.; Hoevers, H.; Kruit, P.

    1994-01-01

    The elemental composition of a sample at nanometer scale is determined by measurement of the characteristic energy of Auger electrons, emitted in coincidence with incoming primary electrons from a microbeam in a scanning transmission electron microscope (STEM). Single electrons are detected with position sensitive detectors, consisting of MicroChannel Plates (MCP) and MultiStrip Anodes (MSA), one for the energy of the Auger electrons (Auger-detector) and one for the energy loss of primary electrons (EELS-detector). The MSAs are sensed with LeCroy 2735DC preamplifiers. The fast readout is based on LeCroy's PCOS III system. On the detection of a coincidence (Event) energy data of Auger and EELS are combined with timing data to an Event word. Event words are stored in list mode in a VME memory module. Blocks of Event words are scanned by transputers in VME and two-dimensional energy histograms are filled using the timing information to obtain a maximal true/accidental ratio. The resulting histograms are stored on disk of a PC-386, which also controls data taking. The system is designed to handle 10 5 Events per second, 90% of which are accidental. In the histograms the ''true'' to ''accidental'' ratio will be 5. The dead time is 15%. ((orig.))

  19. The Use of Celebrity Endorsement with the Help of Electronic Communication Channel (Instagram) : Case study of Magnum Ice Cream in Thailand

    OpenAIRE

    Kutthakaphan, Rangsima; Chokesamritpol, Wahloonluck

    2013-01-01

    TITLE The Use of Celebrity Endorsement with the Help of Electronic Communication Channel (Instagram): Case Study of Magnum Ice Cream Thailand RESEARCH QUESTION How does the use of celebrity endorsement with the help of electronic communication channel (Social media: Instagram) affect the buying behavior of generation Y consumers in Thailand? STRATEGIC QUESTION How can marketers use this marketing technique in an effective way to increase the number of consumers? PURPOSE OF THE STUDY The pu...

  20. Monolithic Chip System with a Microfluidic Channel for In Situ Electron Microscopy of Liquids

    DEFF Research Database (Denmark)

    Jensen, Eric; Burrows, Andrew; Mølhave, Kristian

    2014-01-01

    sandwiched microchips with thin membranes. We report on a new microfabricated chip system based on a monolithic design that enables membrane geometry on the scale of a few micrometers. The design is intended to reduce membrane deflection when the system is under pressure, a micro fluidic channel for improved...

  1. Calculation of spin-dependent observables in electron-sodium scattering using the coupled-channel optical method

    International Nuclear Information System (INIS)

    Bray, Igor.

    1992-04-01

    The calculations of the 3 2 S and 3 2 P spin asymmetries and the angular momentum for singlet and triplet scattering for projectile energies of 10 and 20 eV is presented. Together these observables give a most stringent test of any electron-atom scattering theory. An excellent agreement was found between the results of the coupled-channel optical method and experiment, which for the spin asymmetries can only be obtained by a good description of the couplings between the lower-lying target states and the target continuum. 10 refs., 2 figs

  2. Channelling phenomenon in the gamma irradiated Benzo-quinone and other compounds observed under the scanning electron microscope

    International Nuclear Information System (INIS)

    Suleiman, Y.M.

    1984-01-01

    Scanning Electron Microscope (S.E.M.), has been used to examine the gamma irradiated pure crystals of Benzo-quinone and other compounds in the polycrystaline form. After gamma irradiation, shallow lines (channels) were observed on the crystal's surfaces when the crystal layers arrangements are parallel to the photons beam direction. Holes were also observed when those layers of the crystals are in the nonparallel case. The phenomenon has been studied and analysed in connected with the H-atom bonds disruption, and H-atoms migration through the crystal's layers. (author)

  3. Lack of a peroxiredoxin suppresses the lethality of cells devoid of electron donors by channelling electrons to oxidized ribonucleotide reductase.

    Science.gov (United States)

    Boronat, Susanna; Domènech, Alba; Carmona, Mercè; García-Santamarina, Sarela; Bañó, M Carmen; Ayté, José; Hidalgo, Elena

    2017-06-01

    The thioredoxin and glutaredoxin pathways are responsible of recycling several enzymes which undergo intramolecular disulfide bond formation as part of their catalytic cycles such as the peroxide scavengers peroxiredoxins or the enzyme ribonucleotide reductase (RNR). RNR, the rate-limiting enzyme of deoxyribonucleotide synthesis, is an essential enzyme relying on these electron flow cascades for recycling. RNR is tightly regulated in a cell cycle-dependent manner at different levels, but little is known about the participation of electron donors in such regulation. Here, we show that cytosolic thioredoxins Trx1 and Trx3 are the primary electron donors for RNR in fission yeast. Unexpectedly, trx1 transcript and Trx1 protein levels are up-regulated in a G1-to-S phase-dependent manner, indicating that the supply of electron donors is also cell cycle-regulated. Indeed, genetic depletion of thioredoxins triggers a DNA replication checkpoint ruled by Rad3 and Cds1, with the final goal of up-regulating transcription of S phase genes and constitutive RNR synthesis. Regarding the thioredoxin and glutaredoxin cascades, one combination of gene deletions is synthetic lethal in fission yeast: cells lacking both thioredoxin reductase and cytosolic dithiol glutaredoxin. We have isolated a suppressor of this lethal phenotype: a mutation at the Tpx1-coding gene, leading to a frame shift and a loss-of-function of Tpx1, the main client of electron donors. We propose that in a mutant strain compromised in reducing equivalents, the absence of an abundant and competitive substrate such as the peroxiredoxin Tpx1 has been selected as a lethality suppressor to favor RNR function at the expense of the non-essential peroxide scavenging function, to allow DNA synthesis and cell growth.

  4. Lack of a peroxiredoxin suppresses the lethality of cells devoid of electron donors by channelling electrons to oxidized ribonucleotide reductase.

    Directory of Open Access Journals (Sweden)

    Susanna Boronat

    2017-06-01

    Full Text Available The thioredoxin and glutaredoxin pathways are responsible of recycling several enzymes which undergo intramolecular disulfide bond formation as part of their catalytic cycles such as the peroxide scavengers peroxiredoxins or the enzyme ribonucleotide reductase (RNR. RNR, the rate-limiting enzyme of deoxyribonucleotide synthesis, is an essential enzyme relying on these electron flow cascades for recycling. RNR is tightly regulated in a cell cycle-dependent manner at different levels, but little is known about the participation of electron donors in such regulation. Here, we show that cytosolic thioredoxins Trx1 and Trx3 are the primary electron donors for RNR in fission yeast. Unexpectedly, trx1 transcript and Trx1 protein levels are up-regulated in a G1-to-S phase-dependent manner, indicating that the supply of electron donors is also cell cycle-regulated. Indeed, genetic depletion of thioredoxins triggers a DNA replication checkpoint ruled by Rad3 and Cds1, with the final goal of up-regulating transcription of S phase genes and constitutive RNR synthesis. Regarding the thioredoxin and glutaredoxin cascades, one combination of gene deletions is synthetic lethal in fission yeast: cells lacking both thioredoxin reductase and cytosolic dithiol glutaredoxin. We have isolated a suppressor of this lethal phenotype: a mutation at the Tpx1-coding gene, leading to a frame shift and a loss-of-function of Tpx1, the main client of electron donors. We propose that in a mutant strain compromised in reducing equivalents, the absence of an abundant and competitive substrate such as the peroxiredoxin Tpx1 has been selected as a lethality suppressor to favor RNR function at the expense of the non-essential peroxide scavenging function, to allow DNA synthesis and cell growth.

  5. Semigroups of Herz-Schur multipliers

    DEFF Research Database (Denmark)

    Knudby, Søren

    2014-01-01

    function (see Theorem 1.2). It is then shown that a (not necessarily proper) generator of a semigroup of Herz–Schur multipliers splits into a positive definite kernel and a conditionally negative definite kernel. We also show that the generator has a particularly pleasant form if and only if the group...

  6. A quantum architecture for multiplying signed integers

    International Nuclear Information System (INIS)

    Alvarez-Sanchez, J J; Alvarez-Bravo, J V; Nieto, L M

    2008-01-01

    A new quantum architecture for multiplying signed integers is presented based on Booth's algorithm, which is well known in classical computation. It is shown how a quantum binary chain might be encoded by its flank changes, giving the final product in 2's-complement representation.

  7. Influence of carrier density on the electronic cooling channels of bilayer graphene

    NARCIS (Netherlands)

    Limmer, T.; Houtepen, A.J.; Niggebaum, A.; Tautz, R.; Da Como, E.

    2011-01-01

    We study the electronic cooling dynamics in a single flake of bilayer graphene by femtosecond transient absorption probing the photon-energy range 0.25–1.3 eV. From the transients, we extract the carrier cooling curves for different initial temperatures and densities of the photoexcited electrons

  8. Optical emissions from an ionized channel produced by an electron beam

    International Nuclear Information System (INIS)

    Fessenden, T.J.

    1977-01-01

    Quantitative measurements of the visible light generated by the Astron beam (5 MeV, 400 A) in passing through 500 torr air and nitrogen are reported. Experiments show that in the presence of the beam, the light is from .01 to 0.1 percent sun's brightness. After the beam, the light decays extremely rapidly. The size and position of the beam in the gas can be determined from observations of the channel light

  9. Channeling of electron transport to improve collection efficiency in mesoporous titanium dioxide dye sensitized solar cell stacks

    International Nuclear Information System (INIS)

    Fakharuddin, Azhar; Ahmed, Irfan; Yusoff, Mashitah M.; Jose, Rajan; Khalidin, Zulkeflee

    2014-01-01

    Dye-sensitized solar cell (DSC) modules are generally made by interconnecting large photoelectrode strips with optimized thickness (∼14 μm) and show lower current density (J SC ) compared with their single cells. We found out that the key to achieving higher J SC in large area devices is optimized photoelectrode volume (V D ), viz., thickness and area which facilitate the electron channeling towards working electrode. By imposing constraints on electronic path in a DSC stack, we achieved >50% increased J SC and ∼60% increment in photoelectric conversion efficiency in photoelectrodes of similar V D (∼3.36 × 10 −4 cm 3 ) without using any metallic grid or a special interconnections

  10. Breakdown mechanisms in AlGaN/GaN high electron mobility transistors with different GaN channel thickness values

    International Nuclear Information System (INIS)

    Ma Xiao-Hua; Zhang Ya-Man; Chen Wei-Wei; Wang Xin-Hua; Yuan Ting-Ting; Pang Lei; Liu Xin-Yu

    2015-01-01

    In this paper, the off-state breakdown characteristics of two different AlGaN/GaN high electron mobility transistors (HEMTs), featuring a 50-nm and a 150-nm GaN thick channel layer, respectively, are compared. The HEMT with a thick channel exhibits a little larger pinch-off drain current but significantly enhanced off-state breakdown voltage (BV off ). Device simulation indicates that thickening the channel increases the drain-induced barrier lowering (DIBL) but reduces the lateral electric field in the channel and buffer underneath the gate. The increase of BV off in the thick channel device is due to the reduction of the electric field. These results demonstrate that it is necessary to select an appropriate channel thickness to balance DIBL and BV off in AlGaN/GaN HEMTs. (paper)

  11. Enhancement mode GaN-based multiple-submicron channel array gate-recessed fin metal-oxide-semiconductor high-electron mobility transistors

    Science.gov (United States)

    Lee, Ching-Ting; Wang, Chun-Chi

    2018-04-01

    To study the function of channel width in multiple-submicron channel array, we fabricated the enhancement mode GaN-based gate-recessed fin metal-oxide-semiconductor high-electron mobility transistors (MOS-HEMTs) with a channel width of 450 nm and 195 nm, respectively. In view of the enhanced gate controllability in a narrower fin-channel structure, the transconductance was improved from 115 mS/mm to 151 mS/mm, the unit gain cutoff frequency was improved from 6.2 GHz to 6.8 GHz, and the maximum oscillation frequency was improved from 12.1 GHz to 13.1 GHz of the devices with a channel width of 195 nm, compared with the devices with a channel width of 450 nm.

  12. The Influence of Non-Equilibrium Excitation on the Electron Density in One-Dimensional MFD Channel Flow

    Energy Technology Data Exchange (ETDEWEB)

    Eichert, K.; Kaeppeler, H. J. [Institut fuer Plasmaforschung der Technischen Hochschule Stuttgart, Federal Republic of Germany (Germany)

    1966-10-15

    In previous publications, a system of equations was derived from the gas-kinetic description of a multi-component reacting plasma and employed for the calculation of one-dimensional subsonic flows. This system is now extended to include non-equilibrium excitation. No thermal or chemical equilibrium between the various components of the plasma is assumed. The components of the plasma considered are a non-reacting working fluid, an alkali metal vapour as a seeding material, ions of this seeding substance, and electrons. Three levels for the excited states are introduced. The reactions considered are excitation and ionization by electron collisions, and photo-ionization, as well as the corresponding reverse processes. For the reaction velocities, analytical equations are introduced permitting insertion of any excitation or ionization cross-sections of either experimental or theoretical origin. The method employed had been previously suggested by one of the authors. As examples, the degrees of excitation and ionization in the flow of a helium working fluid with 1% caesium seeding through a channel against transverse magnetic fields of 15 and 40 kg at Mach numbers of 0.7 and 0.8, respectively, were calculated. The results of the calculations show that for relatively small magnetic fields there is no rapid rise of the ionization to Saha-equilibrium as a function of electron temperature. A comparison with the results of a calculation neglecting excitation shows that especially for relatively large magnetic fields non-equilibrium excitation has an essential influence on the electron density and its approach to equilibrium. Neglecting excitation, there results a nearly frozen behaviour of the degree of ionization within channel lengths of technical interest for small magnetic fields. (author)

  13. Characterisation of radiation damage in perovskite using high angular resolution electron channeling x-ray spectroscopy (HARECXS)

    International Nuclear Information System (INIS)

    Smith, K.L.; Zaluzec, N.J.

    2002-01-01

    Full text: Predicting and/or modelling the occurrence of radiation damage induced defects and their effects on physical properties (eg. amorphisation induced swelling, electrical conductivity., optical response etc.) in ceramic phases requires knowledge of the displacement energies, E d , of cations and anions in those phases. In this study, High Angular Resolution Electron Channelling X-ray Spectroscopy (HARECXS) spectra were collected from perovskite (CaTiO 3 ) samples that had been exposed to high-energy electrons or high-energy heavy ions. Calculations based on experimental data were then used to indicate the E d of the cations in perovskite. The HARECXS measurements were conducted on a Philips EM 420T AEM (LaB6 source, operated at 120 kV) fitted with an EDAX ultra thin window Si(Li) detector. The specimen was first manually oriented to an appropriate zone axis. Then control of the relative orientation of the incident probe was accomplished via direct computer control of the beam tilt coils, Typical acquisition times for a complete two-dimensional scan were 18-24 hours, while one dimensional scans ranged from 1-5 hours. Our experiments established that: a) HARECXS can detect radiation damage in perovskite caused by either high energy heavy ions or high energy electrons, b) the HARECXS signature of perovskite shows a systematic change with ion dose, c) HARECXS detects damage in perovskite that has been irradiated with 900kV electrons and does not detect damage in perovskite that has been irradiated with 620kV electrons, indicating the existance of an electron irradiation damage threshold. Calculations based on the latter results indicate that the displacement energy, E d of calcium and titanium in perovskite lie between 50 and 85eV. Copyright (2002) Australian Society for Electron Microscopy Inc

  14. Auger transitions in singly and multiply ionized atoms

    International Nuclear Information System (INIS)

    Mehlhorn, W.

    1978-01-01

    Some recent progress in Auger and autoionizing electron spectrometry of free metal atoms and of multiply ionized atoms is reviewed. The differences which arise between the spectra of atoms in the gaseous and the solid state are due to solid state effects. This will be shown for Cd as an example. The super Coster-Kronig transitions 3p-3d 2 (hole notation) and Coster-Kronig transitions 3p-3d 4s have been measured and compared with free-atom calculations for free Zn atoms. The experimental width GAMMA(3p)=(2.1+-0.2)eV found for the free atom agrees with the value obtained for solid Zn but is considerably smaller than the theoretical value for the free atom. Autoionizing spectra of Na following an L-shell excitation or ionization by different particles are compared and discussed. The nonisotropic angular distribution of electrons from the transition 2p 5 3s 2 2 Psub(3/2)→2p 6 +e - is compared with theoretical calculations. Two examples for Auger spectrometry of multiply ionized atoms are given: (1) excitation of neon target atoms by light and heavy ions, and (2) excitation of projectile ions Be + and B + in single gas collisions with CH 4 . A strong alignment of the excited atoms has also been found here

  15. Progress on channel spark development and application of pulsed electron beam deposition (PED) in the field of medical coating work

    International Nuclear Information System (INIS)

    Schultheiss, Christoph; Buth, Lothar-H.-O.; Frey, Wolfgang; Bluhm, Hansjoachim; Mayer, Hanns-G.

    2002-01-01

    A promising source for Pulsed Electron Beam Deposition (PED) is the channel spark. Recent improvements helped to reduce beam instabilities which up to now have limited the life time of the system. The beam power could be increased and because of better beam quality the transport length of the beam is increased from 1 to several centimeters (up to 10 cm). Together with other improvements on the triggering system and beam transport in dielectric tubes, the channel spark approaches industrial standards. An overview of actual applications in research and industry will be presented. An attractive feature of the pulsed electron beam thin film deposition is the conservation of stoichiometry even during deposition of multi-component earth-alkali and alkali glasses. Specially developed glasses like BIOGLAS registered have the ability to anchor soft living tissue at the surface. In form of a bulk material bio active glasses are brittle limiting its applications. Contrary to brittle bulk material a thin layers on medical implants exhibits reliable bio-functionality. Coating of implants with this category of materials is subject of the European INCOMED project (Innovative Coating of Medical Implants with Soft Tissue Anchoring Ability) which just has started

  16. High-performance all-printed amorphous oxide FETs and logics with electronically compatible electrode/ channel interface.

    Science.gov (United States)

    Sharma, Bhupendra Kumar; Stoesser, Anna; Mondal, Sandeep Kumar; Garlapati, Suresh K; Fawey, Mohammed H; Chakravadhanula, Venkata Sai Kiran; Kruk, Robert; Hahn, Horst; Dasgupta, Subho

    2018-06-12

    Oxide semiconductors typically show superior device performance compared to amorphous silicon or organic counterparts, especially, when they are physical vapor deposited. However, it is not easy to reproduce identical device characteristics when the oxide field-effect transistors (FETs) are solution-processed/ printed; the level of complexity further intensifies with the need to print the passive elements as well. Here, we developed a protocol for designing the most electronically compatible electrode/ channel interface based on the judicious material selection. Exploiting this newly developed fabrication schemes, we are now able to demonstrate high-performance all-printed FETs and logic circuits using amorphous indium-gallium-zinc oxide (a-IGZO) semiconductor, indium tin oxide (ITO) as electrodes and composite solid polymer electrolyte as the gate insulator. Interestingly, all-printed FETs demonstrate an optimal electrical performance in terms of threshold voltages and device mobility and may very well be compared with devices fabricated using sputtered ITO electrodes. This observation originates from the selection of electrode/ channel materials from the same transparent semiconductor oxide family, resulting in the formation of In-Sn-Zn-O (ITZO) based diffused a-IGZO/ ITO interface that controls doping density while ensuring high electrical performance. Compressive spectroscopic studies reveal that Sn doping mediated excellent band alignment of IGZO with ITO electrodes is responsible for the excellent device performance observed. All-printed n-MOS based logic circuits have also been demonstrated towards new-generation portable electronics.

  17. Digital Predistortion of 75-110GHzW-Band Frequency Multiplier for Fiber Wireless Short Range Access Systems

    DEFF Research Database (Denmark)

    Zhao, Ying; Pang, Xiaodan; Deng, Lei

    2011-01-01

    We present a digital predistortion technique to effectively compensate high nonlinearity of a sextuple multiplier operating at 99.6GHz. An 18.9dB adjacent-channel power ratio (ACPR) improvement is guaranteed and a W-band fiber-wireless system is experimentally investigated.......We present a digital predistortion technique to effectively compensate high nonlinearity of a sextuple multiplier operating at 99.6GHz. An 18.9dB adjacent-channel power ratio (ACPR) improvement is guaranteed and a W-band fiber-wireless system is experimentally investigated....

  18. Electron doping through lithium intercalation to interstitial channels in tetrahedrally bonded SiC

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Yuki [Department of Applied Physics, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Center for Computational Materials, Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas 78712 (United States); Oshiyama, Atsushi [Department of Applied Physics, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2015-11-07

    We report on first-principles calculations that clarify the effect of lithium atom intercalation into zinc blende 3C-silicon carbide (3C-SiC) on electronic and structural properties. Lithium atoms inside 3C-SiC are found to donate electrons to 3C-SiC that is an indication of a new way of electron doping through the intercalation. The electrons doped into the conduction band interact with lithium cations and reduce the band spacing between the original valence and conduction bands. We have also found that a silicon monovacancy in 3C-SiC promotes the lithium intercalation, showing that the vacancy generation makes SiC as a possible anode material for lithium-ion battery.

  19. 2.5D direct laser engraving of silicone microfluidic channels for stretchable electronics

    OpenAIRE

    Nagels, Steven; Deferme, Wim

    2017-01-01

    Stretchable and bendable sensors have become increasingly relevant as the technology behind them matures rapidly from lab based to industrially applicable production principles. In a broader sense, stretchable electronics promises to increase the way we are surrounded by and interact with our devices. Electronic circuits will be deployed in environments where we require them to dynamically flex, bend, stretch, compress, twist and - quite possibly - even fold; where they have to demonstrate a ...

  20. Hydrogen retention behavior of beryllides as advanced neutron multipliers

    Directory of Open Access Journals (Sweden)

    Y. Fujii

    2016-12-01

    Full Text Available Beryllium intermetallic compounds (beryllides are the most promising candidate materials for use as advanced neutron multipliers in future fusion reactors because of their low swelling and high stability at high temperatures. Recently, beryllium–titanium beryllide pebbles such as Be12Ti have been successfully fabricated using a novel granulation process. In this study, the fundamental aspects of the behavior of hydrogen isotopes in Be12Ti pebbles were investigated via thermal desorption spectroscopy and transmission electron microscopy. In addition, atomistic calculations using first principles electronic-structure methods were applied to determine the solution energy of hydrogen in Be12Ti. The results showed simpler and weaker hydrogen-trapping efficiency for Be12Ti than for pure Be.

  1. Outer-shell transitions in collisions between multiply charged ions and atoms

    International Nuclear Information System (INIS)

    Bloemen, E.W.P.

    1980-01-01

    The study of collisions between multiply charged ions and atoms (molecules) is of importance in different areas of research. Usually, the most important process is capture of an electron from the target atom into the projectile ion. In most cases the electron goes to an excited state of the projectile ion. These electron capture processes are studied. The author also studied direct excitation of the target atom and of the projectile ion. (Auth.)

  2. The Arabidopsis thylakoid chloride channel AtCLCe functions in chloride homeostasis and regulation of photosynthetic electron transport

    Directory of Open Access Journals (Sweden)

    Andrei eHerdean

    2016-02-01

    Full Text Available Chloride ions can be translocated across cell membranes through Cl− channels or Cl−/H+ exchangers. The thylakoid-located member of the Cl− channel CLC family in Arabidopsis thaliana (AtCLCe was hypothesized to play a role in photosynthetic regulation based on the initial photosynthetic characterization of clce mutant lines. The reduced nitrate content of Arabidopsis clce mutants suggested a role in regulation of plant nitrate homeostasis. In this study, we aimed to further investigate the role of AtCLCe in the regulation of ion homeostasis and photosynthetic processes in the thylakoid membrane. We report that the size and composition of proton motive force were mildly altered in two independent Arabidopsis clce mutant lines. Most pronounced effects in the clce mutants were observed on the photosynthetic electron transport of dark-adapted plants, based on the altered shape and associated parameters of the polyphasic OJIP kinetics of chlorophyll a fluorescence induction. Other alterations were found in the kinetics of state transition and in the macro-organisation of photosystem II supercomplexes, as indicated by circular dichroism measurements. Pre-treatment with KCl but not with KNO3 restored the wild-type photosynthetic phenotype. Analyses by transmission electron microscopy revealed a bow-like arrangement of the thylakoid network and a large thylakoid-free stromal region in chloroplast sections from the dark-adapted clce plants. Based on these data, we propose that AtCLCe functions in Cl− homeostasis after transition from light to dark, which affects chloroplast ultrastructure and regulation of photosynthetic electron transport.

  3. Neutrino oscillation study in the muon neutrino → electron neutrino channel at the Brookhaven accelerator

    International Nuclear Information System (INIS)

    Astier, P.

    1987-09-01

    The E816 experiment described in this thesis is devoted to a neutrino oscillation search at the Brookhaven AGS. The method used here is to look with a fine grained calorimeter for the appearence of electron neutrino in a muon neutrino beam. After recalling the theoretical treatment of the neutrino mass problem, the experimental phenomenology of massive neutrinos and more specifically neutrino oscillations is reviewed. The experiment itself is then extensively described, both on the technical side (detector, beam, simulation) and on the analysis side. In particular the statistical separation of the electromagnetic showers from electrons - our signal - and from photons - our background - treated in detail. The present analysis is based on 2/3 of the final statistics and it leads to the - preliminary - observation of an electron excess in the neutrino interactions yielding 19 ± 15.6 (stat) ± 7 (syst) [fr

  4. Multi-channel electronics for secondary emission grid profile monitor of TTF linac

    International Nuclear Information System (INIS)

    Reingardt-Nikoulin, P.; Gaidash, V.; Mirzojan, A.; Kocharyan, V.; Noelle, D.

    2004-01-01

    According to the TTF beam experimental program, a measurement f the time dependence of the energy spread within the bunch train should be done by means of a standard device for profile measurements, that is Secondary Emission Grid (SEMG). SEMG on the high-energy TTF beam is placed in the focal plane of the magnet spectrometer. It should measure the total energy spread in the range from 0.1% up to a few percents for any single or any group of electron bunches in the bunch train of TTF Linac. SEMG profile measurements with new high sensitive electronics are described. Beam results of SEMG Monitor test are given for two modifications of an electronic preamplifier

  5. Influence of carrier density on the electronic cooling channels of bilayer graphene

    Science.gov (United States)

    Limmer, T.; Houtepen, A. J.; Niggebaum, A.; Tautz, R.; Da Como, E.

    2011-09-01

    We study the electronic cooling dynamics in a single flake of bilayer graphene by femtosecond transient absorption probing the photon-energy range 0.25-1.3 eV. From the transients, we extract the carrier cooling curves for different initial temperatures and densities of the photoexcited electrons and holes. Two regimes of carrier cooling, dominated by optical and acoustic phonons emission, are clearly identified. For increasing carrier density, the crossover between the two regimes occurs at larger carrier temperatures, since cooling via optical phonons experiences a bottleneck. Acoustic phonons, which are less sensitive to saturation, show an increasing contribution at high density.

  6. Equations for the stochastic cumulative multiplying chain

    Energy Technology Data Exchange (ETDEWEB)

    Lewins, J D [Cambridge Univ. (UK). Dept. of Engineering

    1980-01-01

    The forward and backward equations for the conditional probability of the neutron multiplying chain are derived in a new generalization accounting for the chain length and admitting time dependent properties. These Kolmogorov equations form the basis of a variational and hence complete description of the 'lumped' multiplying system. The equations reduce to the marginal distribution, summed over all chain lengths, and to the simpler equations previously derived for that problem. The method of derivation, direct and in the probability space with the minimum of mathematical manipulations, is perhaps the chief attraction: the equations are also displayed in conventional generating function form. As such, they appear to apply to number of problems in areas of social anthropology, polymer chemistry, genetics and cell biology as well as neutron reactor theory and radiation damage.

  7. Equations for the stochastic cumulative multiplying chain

    International Nuclear Information System (INIS)

    Lewins, J.D.

    1980-01-01

    The forward and backward equations for the conditional probability of the neutron multiplying chain are derived in a new generalization accounting for the chain length and admitting time dependent properties. These Kolmogorov equations form the basis of a variational and hence complete description of the 'lumped' multiplying system. The equations reduce to the marginal distribution, summed over all chain lengths, and to the simpler equations previously derived for that problem. The method of derivation, direct and in the probability space with the minimum of mathematical manipulations, is perhaps the chief attraction: the equations are also displayed in conventional generating function form. As such, they appear to apply to number of problems in areas of social anthropology, polymer chemistry, genetics and cell biology as well as neutron reactor theory and radiation damage. (author)

  8. Tourism multipliers in the Mexican economy

    Directory of Open Access Journals (Sweden)

    Antonio Kido-Cruz

    2016-12-01

    Full Text Available This paper presents an analysis of the multiplier impact generated by the tourism sector in Mexico in the year 2013. The importance of studying this sector, in particular, lies in its contribution to the National GDP of over 8% and in its promising development based on services’ quality and the preferred destination of the developed countries. In addition, it is proposed to simulate the multiplier impact that will generate two current events, as they are, the construction of the new International Airport of Mexico and the increase of the investment in Fibers. The results were very punctual, a better distribution of the investment is generated, it is invested in the tourism sector, mainly in variables such as value added and remuneration.

  9. Integrated optic vector-matrix multiplier

    Science.gov (United States)

    Watts, Michael R [Albuquerque, NM

    2011-09-27

    A vector-matrix multiplier is disclosed which uses N different wavelengths of light that are modulated with amplitudes representing elements of an N.times.1 vector and combined to form an input wavelength-division multiplexed (WDM) light stream. The input WDM light stream is split into N streamlets from which each wavelength of the light is individually coupled out and modulated for a second time using an input signal representing elements of an M.times.N matrix, and is then coupled into an output waveguide for each streamlet to form an output WDM light stream which is detected to generate a product of the vector and matrix. The vector-matrix multiplier can be formed as an integrated optical circuit using either waveguide amplitude modulators or ring resonator amplitude modulators.

  10. Development of a six channel Fabry-Perot interferometer for continuous measurement of electron temperature of Tokamak plasma. Application to current diffusion study

    International Nuclear Information System (INIS)

    Talvard, M.

    1984-10-01

    It is shown how the properties of the electron cyclotron emission of a tokamak plasma can be used to measure the electron temperature. The design of a six channel Fabry-Perot interferometer is then described. This interferometer allows the measurement of the time evolution of the electron temperature profile of the plasma in the TFR tokamak. Using this technique interesting results have been obtained concerning the current penetration during the start up phase of a tokamak discharge [fr

  11. Micro-channel plates and vacuum detectors

    Energy Technology Data Exchange (ETDEWEB)

    Gys, T., E-mail: Thierry.Gys@cern.ch

    2015-07-01

    A micro-channel plate is an array of miniature electron multipliers that are each acting as a continuous dynode chain. The compact channel structure results in high spatial and time resolutions and robustness to magnetic fields. Micro-channel plates have been originally developed for night vision applications and integrated as an amplification element in image intensifiers. These devices show single-photon sensitivity with very low noise and have been used as such for scintillating fiber tracker readout in high-energy physics experiments. Given their very short transit time spread, micro-channel plate photomultiplier tubes are also being used in time-of-flight and particle identification detectors. The present paper will cover the history of the micro-channel plate development, basic features, and some of their applications. Emphasis will be put on various new manufacturing processes that have been developed over the last few years, and that result in a significant improvement in terms of efficiency, noise, and lifetime performance.

  12. Tax Multipliers: Pitfalls in Measurement and Identification

    OpenAIRE

    Daniel Riera-Crichton; Carlos A. Vegh; Guillermo Vuletin

    2012-01-01

    We contribute to the literature on tax multipliers by analyzing the pitfalls in identification and measurement of tax shocks. Our main focus is on disentangling the discussion regarding the identification of exogenous tax policy shocks (i.e., changes in tax policy that are not the result of policymakers responding to output fluctuations) from the discussion related to the measurement of tax policy (i.e., finding a tax policy variable under the direct control of the policymaker). For this purp...

  13. Multiplier-free filters for wideband SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Christensen, Erik Lintz

    2001-01-01

    This paper derives a set of parameters to be optimized when designing filters for digital demodulation and range prefiltering in SAR systems. Aiming at an implementation in field programmable gate arrays (FPGAs), an approach for the design of multiplier-free filters is outlined. Design results...... are presented in terms of filter complexity and performance. One filter has been coded in VHDL and preliminary results indicate that the filter can meet a 2 GHz input sample rate....

  14. Mining, regional Australia and the economic multiplier

    Directory of Open Access Journals (Sweden)

    Paul Cleary

    2012-12-01

    Full Text Available Mining in Australia has traditionally delivered a strong development multiplier for regional communities where most mines are based. This relationship has weakened in recent decades as a result of the introduction of mobile workforces - typically known as fly in, fly out. Political parties have responded with policies known as ‘royalties for regions’, though in designing them they overlooked long established Indigenous arrangements for sharing benefits with areas affected directly by mining.

  15. The Uncertainty Multiplier and Business Cycles

    OpenAIRE

    Saijo, Hikaru

    2013-01-01

    I study a business cycle model where agents learn about the state of the economy by accumulating capital. During recessions, agents invest less, and this generates noisier estimates of macroeconomic conditions and an increase in uncertainty. The endogenous increase in aggregate uncertainty further reduces economic activity, which in turn leads to more uncertainty, and so on. Thus, through changes in uncertainty, learning gives rise to a multiplier effect that amplifies business cycles. I use ...

  16. Analyses of electron runaway in front of the negative streamer channel

    DEFF Research Database (Denmark)

    Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.

    2017-01-01

    X-and γ-ray emissions, observed in correlation with negative leaders of lightning and long sparks of high-voltage laboratory experiments, are conventionally connected with the bremsstrahlung of high-energy runaway electrons (REs). Here we extend a focusing mechanism, analyzed in our previous paper...

  17. Electron-molecular cation reactive collisions: from channel mixing to competitive processes

    International Nuclear Information System (INIS)

    Motapon, O; Tamo, F O Waffeu; Backodissa, D; Chakrabarti, K; Mezei, J. Zs; Lique, F; Schneider, I F; Tudorache, D; Bultel, A; Tchang-Brillet, L; Dulieu, O; Tennyson, J; Wolf, A; Urbain, X

    2011-01-01

    The competition between dissociative recombination, vibrational excitation, and dissociative excitation of molecular cations in electron-impact collisions is discussed within the formalism of the Multichannel Quantum Defect Theory. Illustrative results are given for the HD + /HD and CO + /CO systems.

  18. Research of transportation efficiency of low-energy high- current electron beam in plasma channel in external magnetic field

    International Nuclear Information System (INIS)

    Vagin, E S; Grigoriev, V P

    2015-01-01

    Effective high current (5-20 kA) and low energy (tens of keV) electrons beam transportation is possible only with almost complete charging neutralization. It is also necessary to use quite high current neutralization for elimination beam self-pinching effect. The research is based on the self-consistent mathematical model that takes into account beam and plasma particles dynamic, current and charge neutralization of electron beam and examines the transportation of electron beam into a chamber with low-pressure plasma in magnetic field. A numerical study was conducted using particle in cell (PIC) method. The study was performed with various system parameters: rise time and magnitude of the beam current, gas pressure and plasma density and geometry of the system. Regularities of local virtual cathode field generated by the beam in the plasma channel, as well as ranges of parameters that let transportation beam with minimal losses, depending on the external magnetic field were determined through a series of numerical studies. In addition, the assessment of the impact of the plasma ion mobility during the transition period and during steady beam was performed. (paper)

  19. Isometric multipliers of a vector valued Beurling algebra on a ...

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences; Volume 127; Issue 1. Isometric multipliers of a vector valued Beurling algebra on a discrete semigroup. Research Article Volume 127 Issue 1 February 2017 pp 109- ... Keywords. Weighted semigroup; multipliers of a semigroup; Beurling algebra; isometric multipliers.

  20. Non-channel magnetron gun as the electron source for resonance linear accelerator

    International Nuclear Information System (INIS)

    Ivanov, G.M.; Makhnenko, L.A.; Cherenshchikov, S.A.

    1999-01-01

    Studies on the magnetron gun with a cold cathode being part of linear accelerator on the travelling wave are described. Two modes of the gun operation differing by presence of UHF field of the pre-buncher near the gun are observed. In the mode without UHF field the short (about 2 ns) pulses of accelerated electrons with amplitude up to 0.5 A at the gun current up to 20 A were obtained. The presence of UHF field near the gun makes it possible to obtain the beam of higher duration (up to 1.0 μs), but with current up to 20 mA at the accelerator outlet and up to 1 A at the gun outlet. The mechanism of the gun operation is concerned with the secondary-electron current increase and setting self-sustaining secondary emission. Gun characteristics under study are acceptable for the purposes of injection into accelerator [ru

  1. Electron Impact Ionization of C60

    International Nuclear Information System (INIS)

    Duenser, B.; Lezius, M.; Scheier, P.; Deutsch, H.; Maerk, T.D.

    1995-01-01

    Absolute partial and total cross sections for the electron impact ionization of C 60 have been measured using a novel approach for the absolute calibration. The results obtained reveal not only an anomalous large parent ion cross section (as compared to the other ionization channels), but also anomalies for the production of multiply charged parent and fragment ions. This special behavior has its origin in the specific electronic and geometric structure of C 60 . Semiclassical calculations for singly charged ions support the measured data

  2. Photoionization and Electron Transfer of Biphenyl within the Channels of Al-ZSM-5 Zeolites.

    Science.gov (United States)

    Gener, Isabelle; Buntinx, Guy; Brémard, Claude

    1999-06-14

    Evidence of the photogenerated long-lived biphenyl radical and a trapped electron in the void space of aluminated nonacidic ZSM-5 zeolites has been obtained from the time-resolved UV/Vis absorption, Raman scattering, and EPR spectra. The restoration of the ground states implicates the existence of long-lived positive holes in the framework. © 1999 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

  3. Electron spin-echo envelope modulation (ESEEM) reveals water and phosphate interactions with the KcsA potassium channel.

    Science.gov (United States)

    Cieslak, John A; Focia, Pamela J; Gross, Adrian

    2010-02-23

    Electron spin-echo envelope modulation (ESEEM) spectroscopy is a well-established technique for the study of naturally occurring paramagnetic metal centers. The technique has been used to study copper complexes, hemes, enzyme mechanisms, micellar water content, and water permeation profiles in membranes, among other applications. In the present study, we combine ESEEM spectroscopy with site-directed spin labeling (SDSL) and X-ray crystallography in order to evaluate the technique's potential as a structural tool to describe the native environment of membrane proteins. Using the KcsA potassium channel as a model system, we demonstrate that deuterium ESEEM can detect water permeation along the lipid-exposed surface of the KcsA outer helix. We further demonstrate that (31)P ESEEM is able to identify channel residues that interact with the phosphate headgroup of the lipid bilayer. In combination with X-ray crystallography, the (31)P data may be used to define the phosphate interaction surface of the protein. The results presented here establish ESEEM as a highly informative technique for SDSL studies of membrane proteins.

  4. Drawing the geometry of 3d transition metal-boron pairs in silicon from electron emission channeling experiments

    CERN Document Server

    Silva, Daniel; Wahl, Ulrich; Martins Correia, Joao; Augustyns, Valerie; De Lemos Lima, Tiago Abel; Granadeiro Costa, Angelo Rafael; David Bosne, Eric; Castro Ribeiro Da Silva, Manuel; Esteves De Araujo, Araujo Joao Pedro; Da Costa Pereira, Lino Miguel

    2016-01-01

    Although the formation of transition metal-boron pairs is currently well established in silicon processing, the geometry of these complexes is still not completely understood. We investigated the lattice location of the transition metals manganese, iron, cobalt and nickel in n- and p+-type silicon by means of electron emission channeling. For manganese, iron and cobalt, we observed an increase of sites near the ideal tetrahedral interstitial position by changing the doping from n- to p+-type Si. Such increase was not observed for Ni. We ascribe this increase to the formation of pairs with boron, driven by Coulomb interactions, since the majority of iron, manganese and cobalt is positively charged in p+-type silicon while Ni is neutral. We propose that breathing mode relaxation around the boron ion within the pair causes the observed displacement from the ideal tetrahedral interstitial site. We discuss the application of the emission channeling technique in this system and, in particular, how it provides insi...

  5. Calculation of the electron wave function in a graded-channel double-heterojunction modulation-doped field-effect transistor

    Science.gov (United States)

    Mui, D. S. L.; Patil, M. B.; Morkoc, H.

    1989-01-01

    Three double-heterojunction modulation-doped field-effect transistor structures with different channel composition are investigated theoretically. All of these transistors have an In(x)Ga(1-x)As channel sandwiched between two doped Al(0.3)Ga(0.7)As barriers with undoped spacer layers. In one of the structures, x varies from 0 from either heterojunction to 0.15 at the center of the channel quadratically; in the other two, constant values of x of 0 and 0.15 are used. The Poisson and Schroedinger equations are solved self-consistently for the electron wave function in all three cases. The results showed that the two-dimensional electron gas (2DEG) concentration in the channel of the quadratically graded structure is higher than the x = 0 one and slightly lower than the x = 0.15 one, and the mean distance of the 2DEG is closer to the center of the channel for this transistor than the other two. These two effects have important implications on the electron mobility in the channel.

  6. Reduced thermal resistance in AlGaN/GaN multi-mesa-channel high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Asubar, Joel T., E-mail: joel@rciqe.hokudai.ac.jp; Yatabe, Zenji; Hashizume, Tamotsu [Research Center for Integrated Quantum Electronics (RCIQE) and Graduate School of Information Science and Technology, Hokkaido University, Sapporo (Japan); Japan Science and Technology Agency (JST), CREST, 102-0075 Tokyo (Japan)

    2014-08-04

    Dramatic reduction of thermal resistance was achieved in AlGaN/GaN Multi-Mesa-Channel (MMC) high electron mobility transistors (HEMTs) on sapphire substrates. Compared with the conventional planar device, the MMC HEMT exhibits much less negative slope of the I{sub D}-V{sub DS} curves at high V{sub DS} regime, indicating less self-heating. Using a method proposed by Menozzi and co-workers, we obtained a thermal resistance of 4.8 K-mm/W at ambient temperature of ∼350 K and power dissipation of ∼9 W/mm. This value compares well to 4.1 K-mm/W, which is the thermal resistance of AlGaN/GaN HEMTs on expensive single crystal diamond substrates and the lowest reported value in literature.

  7. Near-GeV-energy laser-wakefield acceleration of self-injected electrons in a centimeter-scale plasma channel

    International Nuclear Information System (INIS)

    Tsung, F.S.; Narang, Ritesh; Joshi, C.; Mori, W. B.; Fonseca, R. A.; Silva, L.O.

    2004-01-01

    The first three-dimensional, particle-in-cell (PIC) simulations of laser-wakefield acceleration of self-injected electrons in a 0.84 cm long plasma channel are reported. The frequency evolution of the initially 50 fs (FWHM) long laser pulse by photon interaction with the wake followed by plasma dispersion enhances the wake which eventually leads to self-injection of electrons from the channel wall. This first bunch of electrons remains spatially highly localized. Its phase space rotation due to slippage with respect to the wake leads to a monoenergetic bunch of electrons with a central energy of 0.26 GeV after 0.55 cm propagation. At later times, spatial bunching of the laser enhances the acceleration of a second bunch of electrons to energies up to 0.84 GeV before the laser pulse intensity is significantly reduced

  8. Coupled-channel optical calculation of electron-atom scattering: elastic scattering from sodium at 20 to 150 eV

    International Nuclear Information System (INIS)

    Bray, Igor; Konovalov, D.A.; McCarthy, I.E.

    1991-04-01

    A coupled-channel optical method for electron-atom scattering is applied to elastic electron-sodium scattering at energies of 20, 22.1, 54.4, 100, and 150 eV. It is demonstrated that the effect of all the inelastic channels on elastic scattering may be well reproduced by the 'ab initio' calculated complex non-local polarization potential. Whilst the experiments generally agree at small angles and therefore agree on the total elastic cross section, there is considerable discrepancy at intermediate and backward angles. 9 refs., 2 tabs., 1 fig

  9. Analysis of Z boson production in the electron channel with the CMS detector at the LHC

    CERN Document Server

    Marchica, Carmelo

    2010-01-01

    A Monte Carlo (MC) analysis of Z bosons, based on the selection of electrons and positrons which will be produced at the LHC, is presented. In doing so, a full simulation based on the CMS detector was taken into account. Owing to a lack of data, a small dataset, so called pseudo data, with an integrated luminosity of 10 pb 1 , at a center-of-mass energy of 10 TeV, was used. A simple and robust electron/positron selection procedure for the central part of the detector was devised. It was shown that this selection leads to practically background free sample of Z bosons. Based on the Z boson counting, with a statistical uncertainty of 3%, an eciency correction of 3% and the uncertainty on the integrated luminosity of about 11%, the Z boson cross-section could be calculated and compared to its theoretical value. In addition, the same counting method was used to calculate the integrated luminosity to 6%, which is mainly due to a theoretical uncertainty of about 5%. Various distributions, such as rapidity and trans...

  10. Study of heterogeneous multiplying and non-multiplying media by the neutron pulsed source technique

    International Nuclear Information System (INIS)

    Deniz, V.

    1969-01-01

    The pulsed neutron technique consists essentially in sending in the medium to be studied a short neutron pulse and in determining the asymptotic decay constant of the generated population. The variation of the decay constant as a function of the size of the medium allows the medium characteristics to be defined. This technique has been largely developed these last years and has been applied as well to moderator as to multiplying media, in most cases homogeneous ones. We considered of interest of apply this technique to lattices, to see if useful informations could be collected for lattice calculations. We present here a general theoretical study of the problem, and results and interpretation of a series of experiments made on graphite lattices. There is a good agreement for non-multiplying media. In the case of multiplying media, it is shown that the age value used until now in graphite lattices calculations is over-estimated by about 10 per cent [fr

  11. A high reliability automatic multiplier for a mass spectrometer ion detector circuit

    International Nuclear Information System (INIS)

    Hoshino, Kiichi; Satooka, Sakae

    1978-01-01

    An automatic multiplier of an ion detector circuit for measurement of isotopic abundance ratio of heavy hydrogen to be used with a single collector has been constructed. This multiplier works at 1/1, 1/5, 1/20, 1/100, 1/500, 1/2000 and infinity, and the input voltage which is required to change the range from 1/1 to 1/5 is 10 mV and that from 1/2000 to infinity is 20 V. As the amplifier preceding the automatic multiplier, a vibrating reed electrometer which generates maximum output of 30 V is used. On measurement, marks which indicate the magnifications are recorded on the chart of electronic recorder. It is possible to set the minimum magnification at 1/1, 1/5, or 1/20 by a switch for setting the minimum magnification. (author)

  12. Transient phenomena in bounded fast multiplying assemblies

    International Nuclear Information System (INIS)

    Kraft, T.E.

    1976-01-01

    A generalized dispersion formalism is developed in the context of time-, space-, and energy-dependent transport theory. The evolution of the neutron population in a fast multiplying system following an initial burst of neutrons is examined. The generalized dispersion law obtained is an integral equation, in one variable, for the Laplace and Fourier transformed time- and space-dependent sources of fission neutrons. An approximation technique is shown to generate solutions which converge in L 2 norm to the exact solution for exact elastic, exact inelastic, Goertzel-Grueling or Wigner scattering kernels, and any reasonable fission spectrum

  13. Quasiparticle trapping and the quasiparticle multiplier

    International Nuclear Information System (INIS)

    Booth, N.E.

    1987-01-01

    Superconductors and in particular superconducting tunnel junctions can be used to detect phonons, electromagnetic radiation, x rays, and nuclear particles by the mechanism of Cooper-pair breaking to produce excess quasiparticles and phonons. We show that the sensitivity can be increased by a factor of 100 or more by trapping the quasiparticles in another superconductor of lower gap in the region of the tunnel junction. Moreover, if the ratio of the gap energies is >3 a multiplication process can occur due to the interaction of the relaxation phonons. This leads to the concept of the quasiparticle multiplier, a device which could have wider applications than the Gray effect transistor or the quiteron

  14. Multipliers on Generalized Mixed Norm Sequence Spaces

    Directory of Open Access Journals (Sweden)

    Oscar Blasco

    2014-01-01

    Full Text Available Given 1≤p,q≤∞ and sequences of integers (nkk and (nk′k such that nk≤nk′≤nk+1, the generalized mixed norm space ℓℐ(p,q is defined as those sequences (ajj such that ((∑j∈Ik‍|aj|p1/pk∈ℓq where Ik={j∈ℕ0 s.t. nk≤jmultipliers (ℓℐ(r,s,ℓ(u,v, for different sequences ℐ and of intervals in ℕ0, are determined.

  15. Synthesis of highly faceted multiply twinned gold nanocrystals stabilized by polyoxometalates

    International Nuclear Information System (INIS)

    Yuan Junhua; Chen Yuanxian; Han Dongxue; Zhang Yuanjian; Shen Yanfei; Wang Zhijuan; Niu Li

    2006-01-01

    A novel and facile chemical synthesis of highly faceted multiply twinned gold nanocrystals is reported. The gold nanocrystals are hexagonal in transmission electron microscopy and icosahedral in scanning electron microscopy. Phosphotungstic acid (PTA), which was previously reduced, serves as a reductant and stabilizer for the synthesis of gold nanocrystals. The PTA-gold nanocomposites are quite stable in aqueous solutions, and electrochemically active towards the hydrogen evolution reaction

  16. The effects of drain scatterings on the electron transport properties of strained-Si diodes with ballistic and non-ballistic channels

    International Nuclear Information System (INIS)

    Yasenjan Ghupur; Mamtimin Geni; Mamatrishat Mamat; Abudukelimu Abudureheman

    2015-01-01

    The effects of multiple scattering on the electron transport properties in drain regions are numerically investigated for the cases of strained-Si diodes with or without scattering in the channel. The performance of non-ballistic (with scattering) channel Si-diodes is compared with that of ballistic (without scattering) channel Si-diodes, using the strain and scattering model. Our results show that the values of the electron velocity and the current in the strain model are higher than the respective values in the unstrained model, and the values of the velocity and the current in the ballistic channel model are higher than the respective values in the non-ballistic channel model. In the strain and scattering models, the effect of each carrier scattering mechanism on the performance of the Si-diodes is analyzed in the drain region. For the ballistic channel model, our results show that inter-valley optical phonon scattering improves device performance, whereas intra-valley acoustic phonon scattering degrades device performance. For the strain model, our results imply that the larger energy splitting of the strained Si could suppress the inter-valley phonon scattering rate. In conclusion, for the drain region, investigation of the strained-Si and scattering mechanisms are necessary, in order to improve the performance of nanoscale ballistic regime devices. (paper)

  17. Suppression of surface-originated gate lag by a dual-channel AlN/GaN high electron mobility transistor architecture

    International Nuclear Information System (INIS)

    Deen, David A.; Storm, David F.; Scott Katzer, D.; Bass, R.; Meyer, David J.

    2016-01-01

    A dual-channel AlN/GaN high electron mobility transistor (HEMT) architecture is demonstrated that leverages ultra-thin epitaxial layers to suppress surface-related gate lag. Two high-density two-dimensional electron gas (2DEG) channels are utilized in an AlN/GaN/AlN/GaN heterostructure wherein the top 2DEG serves as a quasi-equipotential that screens potential fluctuations resulting from distributed surface and interface states. The bottom channel serves as the transistor's modulated channel. Dual-channel AlN/GaN heterostructures were grown by molecular beam epitaxy on free-standing hydride vapor phase epitaxy GaN substrates. HEMTs fabricated with 300 nm long recessed gates demonstrated a gate lag ratio (GLR) of 0.88 with no degradation in drain current after bias stressed in subthreshold. These structures additionally achieved small signal metrics f_t/f_m_a_x of 27/46 GHz. These performance results are contrasted with the non-recessed gate dual-channel HEMT with a GLR of 0.74 and 82 mA/mm current collapse with f_t/f_m_a_x of 48/60 GHz.

  18. Suppression of surface-originated gate lag by a dual-channel AlN/GaN high electron mobility transistor architecture

    Science.gov (United States)

    Deen, David A.; Storm, David F.; Scott Katzer, D.; Bass, R.; Meyer, David J.

    2016-08-01

    A dual-channel AlN/GaN high electron mobility transistor (HEMT) architecture is demonstrated that leverages ultra-thin epitaxial layers to suppress surface-related gate lag. Two high-density two-dimensional electron gas (2DEG) channels are utilized in an AlN/GaN/AlN/GaN heterostructure wherein the top 2DEG serves as a quasi-equipotential that screens potential fluctuations resulting from distributed surface and interface states. The bottom channel serves as the transistor's modulated channel. Dual-channel AlN/GaN heterostructures were grown by molecular beam epitaxy on free-standing hydride vapor phase epitaxy GaN substrates. HEMTs fabricated with 300 nm long recessed gates demonstrated a gate lag ratio (GLR) of 0.88 with no degradation in drain current after bias stressed in subthreshold. These structures additionally achieved small signal metrics ft/fmax of 27/46 GHz. These performance results are contrasted with the non-recessed gate dual-channel HEMT with a GLR of 0.74 and 82 mA/mm current collapse with ft/fmax of 48/60 GHz.

  19. Suppression of surface-originated gate lag by a dual-channel AlN/GaN high electron mobility transistor architecture

    Energy Technology Data Exchange (ETDEWEB)

    Deen, David A., E-mail: david.deen@alumni.nd.edu; Storm, David F.; Scott Katzer, D.; Bass, R.; Meyer, David J. [Naval Research Laboratory, Electronics Science and Technology Division, Washington, DC 20375 (United States)

    2016-08-08

    A dual-channel AlN/GaN high electron mobility transistor (HEMT) architecture is demonstrated that leverages ultra-thin epitaxial layers to suppress surface-related gate lag. Two high-density two-dimensional electron gas (2DEG) channels are utilized in an AlN/GaN/AlN/GaN heterostructure wherein the top 2DEG serves as a quasi-equipotential that screens potential fluctuations resulting from distributed surface and interface states. The bottom channel serves as the transistor's modulated channel. Dual-channel AlN/GaN heterostructures were grown by molecular beam epitaxy on free-standing hydride vapor phase epitaxy GaN substrates. HEMTs fabricated with 300 nm long recessed gates demonstrated a gate lag ratio (GLR) of 0.88 with no degradation in drain current after bias stressed in subthreshold. These structures additionally achieved small signal metrics f{sub t}/f{sub max} of 27/46 GHz. These performance results are contrasted with the non-recessed gate dual-channel HEMT with a GLR of 0.74 and 82 mA/mm current collapse with f{sub t}/f{sub max} of 48/60 GHz.

  20. New Lagrange Multipliers for the Blind Adaptive Deconvolution Problem Applicable for the Noisy Case

    Directory of Open Access Journals (Sweden)

    Monika Pinchas

    2016-02-01

    Full Text Available Recently, a new blind adaptive deconvolution algorithm was proposed based on a new closed-form approximated expression for the conditional expectation (the expectation of the source input given the equalized or deconvolutional output where the output and input probability density function (pdf of the deconvolutional process were approximated with the maximum entropy density approximation technique. The Lagrange multipliers for the output pdf were set to those used for the input pdf. Although this new blind adaptive deconvolution method has been shown to have improved equalization performance compared to the maximum entropy blind adaptive deconvolution algorithm recently proposed by the same author, it is not applicable for the very noisy case. In this paper, we derive new Lagrange multipliers for the output and input pdfs, where the Lagrange multipliers related to the output pdf are a function of the channel noise power. Simulation results indicate that the newly obtained blind adaptive deconvolution algorithm using these new Lagrange multipliers is robust to signal-to-noise ratios (SNR, unlike the previously proposed method, and is applicable for the whole range of SNR down to 7 dB. In addition, we also obtain new closed-form approximated expressions for the conditional expectation and mean square error (MSE.

  1. Coupled-channel optical calculation of electron-hydrogen scattering: elastic scattering from 0.5 to 30 eV

    International Nuclear Information System (INIS)

    Bray, I.; Konovalov, D.A.; McCarthy, I.E.

    1991-01-01

    A coupled-channel optical method for electron-atomic hydrogen scattering is presented in a form that treats both the projectile and the target electrons symmetrically. Elastic differential cross sections are calculated at a range of energies from 0.5 to 30 eV and are found to be in complete agreement with the absolute measurements, previously reported. Total and total ionization cross sections are also presented. 13 refs., 2 tabs., 2 figs

  2. Rhinoplasty for the multiply revised nose.

    Science.gov (United States)

    Foda, Hossam M T

    2005-01-01

    To evaluate the problems encountered on revising a multiply operated nose and the methods used in correcting such problems. The study included 50 cases presenting for revision rhinoplasty after having had 2 or more previous rhinoplasties. An external rhinoplasty approach was used in all cases. Simultaneous septal surgery was done whenever indicated. All cases were followed for a mean period of 32 months (range, 1.5-8 years). Evaluation of the surgical result depended on clinical examination, comparison of pre- and postoperative photographs, and degree of patients' satisfaction with their aesthetic and functional outcome. Functionally, 68% suffered nasal obstruction that was mainly caused by septal deviations and nasal valve problems. Aesthetically, the most common deformities of the upper two thirds of the nose included pollybeak (64%), dorsal irregularities (54%), dorsal saddle (44%), and open roof deformity (42%), whereas the deformities of lower third included depressed tip (68%), tip contour irregularities (60%), and overrotated tip (42%). Nasal grafting was necessary in all cases; usually more than 1 type of graft was used in each case. Postoperatively, 79% of the patients, with preoperative nasal obstruction, reported improved breathing; 84% were satisfied with their aesthetic result; and only 8 cases (16%) requested further revision to correct minor deformities. Revision of a multiply operated nose is a complex and technically demanding task, yet, in a good percentage of cases, aesthetic as well as functional improvement are still possible.

  3. Quantum mechanics in a multiply connected region

    International Nuclear Information System (INIS)

    Miyazawa, H.

    1986-01-01

    It is usually assumed that wave fields or wave functions are single valued functions of space-time. However, the phase of a complex field is an unobservable quantity and there is no obvious reason that it must be single valued. On this point quantum mechanics in a multiply connected regions is not well formulated. This ambiguity appears e.g., in the case of the Bohm-Aharonov effect concerning the observability of the vector potential around a magnetic flux. The author discusses the single or multiple valuedness of wave functions and attempts to see if such an effect really exists or not. The wave function of a charged particle in a multiply connected region is not necessarily single valued. The condition that the ground state energy be a minimum fixes the character of the multiple valuedness. For a charged particle around a magnetic flux a multiple valued wave function is preferable and no Bohm-Aharonov effect is observed. The minimum energy principle is proved if one also considers the interaction of a charged particle with external objects. Then theoretically the Bohm-Aharonov effect should not be observed. Experiments are not yet conclusive on this point

  4. Search for electroweak top quark production in the electron + jets channel in the D0 experiment at the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Busato, Emmanuel [Paris Univ. (France)

    2005-04-01

    The top quark, whose mass approaches the electroweak symmetry breaking scale, is by far the heaviest known elementary particle. New physics is therefore expected to have its most important effect in the top sector. The Tevatron is, currently, the only collider able to produce the top quark. Among all possible production processes in the standard model, the top-antitop pair production via strong interaction, first observed in 1995, is the one with the largest cross section. The production via electroweak interaction (known as single top production), more difficult to extract from the background because of a lower cross section and of a lower signal to background ratio, has never been observed. In this thesis, we have searched for these processes by studying proton-antiproton collisions at $\\sqrt{s}$ =1.96 TeV produced by the Tevatron and detected with the DØ detector. The experimental study of the top quark is very sensitive to the quality of the data taken by the calorimeter. This detector showed, at the beginning of the Run II, rather important noise problems. Having identified the origin of the noise, new treatments at the offline level were implemented and their effects studied. It has been shown that these treatments reduce very significantly the effect of the noise in the reconstruction of physical quantities without notable degradation of the signal. Within the standard model, the top quark decays into W b with a branching ratio close to 100%. Leptonic decays of the into electron + neutrino have been used to identify the from the top decay. The main backgrounds to the single top signal ( +jets and QCD) are made essentially of light quark jets in the final state. Two ..-tagging algorithms have therefore been applied in order to improve the signal to background ratio. No evidence for electroweak top quark production has been found. Upper limits at the 95 % confidence level on the observed (expected) cross sections have be computed. They are found to be 14

  5. Hadamard Multipliers and Abel Dual of Hardy Spaces

    Directory of Open Access Journals (Sweden)

    Paweł Mleczko

    2016-01-01

    Full Text Available The paper is devoted to the study of Hadamard multipliers of functions from the abstract Hardy classes generated by rearrangement invariant spaces. In particular the relation between the existence of such multiplier and the boundedness of the appropriate convolution operator on spaces of measurable functions is presented. As an application, the description of Hadamard multipliers into H∞ is given and the Abel type theorem for mentioned Hardy spaces is proved.

  6. φ-Multipliers on Banach Algebras and Topological Modules

    OpenAIRE

    Adib, Marjan

    2015-01-01

    We prove some results concerning Arens regularity and amenability of the Banach algebra ${M}_{\\phi }(A)$ of all $\\phi $ -multipliers on a given Banach algebra $A$ . We also consider $\\phi $ -multipliers in the general topological module setting and investigate some of their properties. We discuss the $\\phi $ -strict and $\\phi $ -uniform topologies on ${M}_{\\phi }(A)$ . A characterization of $\\phi $ -multipliers on ${L}_{1}(G)$ -module ${L}_{p}(G)$ , where $G$ is a compact group, is given.

  7. A Multi-Channel Opto-Electronic Sensor to Accurately Monitor Heart Rate against Motion Artefact during Exercise

    Directory of Open Access Journals (Sweden)

    Abdullah Alzahrani

    2015-10-01

    Full Text Available This study presents the use of a multi-channel opto-electronic sensor (OEPS to effectively monitor critical physiological parameters whilst preventing motion artefact as increasingly demanded by personal healthcare. The aim of this work was to study how to capture the heart rate (HR efficiently through a well-constructed OEPS and a 3-axis accelerometer with wireless communication. A protocol was designed to incorporate sitting, standing, walking, running and cycling. The datasets collected from these activities were processed to elaborate sport physiological effects. t-test, Bland-Altman Agreement (BAA, and correlation to evaluate the performance of the OEPS were used against Polar and Mio-Alpha HR monitors. No differences in the HR were found between OEPS, and either Polar or Mio-Alpha (both p > 0.05; a strong correlation was found between Polar and OEPS (r: 0.96, p < 0.001; the bias of BAA 0.85 bpm, the standard deviation (SD 9.20 bpm, and the limits of agreement (LOA from −17.18 bpm to +18.88 bpm. For the Mio-Alpha and OEPS, a strong correlation was found (r: 0.96, p < 0.001; the bias of BAA 1.63 bpm, SD 8.62 bpm, LOA from −15.27 bpm to +18.58 bpm. These results demonstrate the OEPS to be capable of carrying out real time and remote monitoring of heart rate.

  8. Emittance growth of an electron beam in a periodic channel due to transfer of longitudinal energy to transverse energy

    International Nuclear Information System (INIS)

    Carlsten, B.E.

    1998-01-01

    Most discussions about emittance growth and halo production for an intense electron beam in a periodic focusing channel assume that the total transverse energy is constant (or, in other words, that the transverse and longitudinal Hamiltonians are separable). Previous analyses that include variations in the total transverse energy are typically based on a transverse-longitudinal coupling that is either from two-dimensional space-charge modes or particle-particle Coulomb collisions. With the space-charge modes, the energy exchange between the transverse and longitudinal directions is periodic, and of constant magnitude. The total energy transfer for the case of the Coulomb collisions is negligible. This limited increase of energy in the transverse direction from these other effects will limit the amount of transverse emittance growth possible. In this paper, the authors investigate a mechanism in which there is a continual transfer of energy from the longitudinal direction to the transverse direction, leading to essentially unlimited potential transverse emittance growth. This mechanism is caused by an asymmetry of the beam's betatron motion within the periodic focusing elements. This analysis is based on thermodynamic principles. This mechanism exists for both solenoids and quadrupole focusing, although only solenoid focusing is studied here

  9. Site determination of Ni atoms in Cu-Al-Ni shape memory alloys by electron channelling enhanced microanalysis

    International Nuclear Information System (INIS)

    Nakata, Yoshiyuki; Tadaki, Tsugio; Shimizu, Ken-ichi

    1990-01-01

    The crystallographic site of Ni atoms in the parent phase of differently heat-treated Cu-28.6Al-3.7Ni (at.%) shape memory alloys has been examined by electron channelling enhanced microanalysis (ALCHEMI) in order to clarify effects of heat-treatments on the Ni atom site and M s temperature. The heat-treatments were as follows: (a) Quenching into a 10% NaOH solution at 263 K, (b) Quenching into hot water at 363 K and (c) Aging at 523 K for 3.6 ks after treatment (b). The M s temperatures of specimens (a), (b) and (c) were 158, 185 and 259 K, respectively, increasing with lowering quenching rate or aging. ALCHEMI revealed that Ni atoms occupied an identical site in all the three kinds of specimens: The Ni atoms were located at the nearest neighbor sites around Al atoms. This preferential occupation of Ni atoms was attributed to the strong binding force between Ni and Al atoms. Thus, the change in M s temperature due to different heat-treatments was not directly related to the crystallographic site of Ni atoms, but might be caused by the ordering between the next nearest neighbor Cu and Al atoms. (author)

  10. Design and features of the target tracker of the Opera's target: study of the electron channel events

    International Nuclear Information System (INIS)

    Chon-Sen, N.

    2009-01-01

    Neutrino oscillations are now well acknowledged, the purpose of the Opera experiment is to show how ν τ appear in a ν μ beam. The ν μ beam is produced at CERN and crosses the earth crust on a distance of 732 km before being detected in the Gran-Sasso underground laboratory. The Opera experiment uses the technique of the photographic emulsion. The detector target is a series of walls of lead bricks, each brick being made of photographic emulsions intercalated with lead sheets. A target tracker enables the localization of the brick in which the neutrino interaction has happened. As soon as the brick is found, the brick is removed from the detector and the emulsion is developed and analysed. the target tracker is made up of plastic scintillator bars on which optic fibers are stuck to collect photons and send them to photomultipliers. The main purpose of this work is the calibration of the target tracker. The first chapter introduces the standard model, the neutrino and the neutrino oscillation phenomenon. The second chapter reviews the neutrino experiments worldwide. The third chapter describes the Opera experiment while chapter 4 and 5 are dedicated to the design and operation of the target tracker. The last chapter studies through simulation the behaviour of the target tracker when submitted to an electron beam in order to use it as a complementary tool for the identification of the τ → e channel. (A.C.)

  11. Neutron multiplier alternative for fusion reactor blankets

    International Nuclear Information System (INIS)

    Taczanowski, S.

    1980-01-01

    A proposal is given to replace neutron multiplier needed to enable low lithium and tritium inventories simultaneously assuring sufficient production of tritium, by an efficient moderator ( 7 LiH or 7 LiD). The advantageous effect of the intensified neutron energy degradation is due to the 1/v character of the main tritium producing reaction. The slowing-down medium is designed to be the source of moderated neutrons for the surrounding Li ( 6 Li enriched) region where the most of tritium is to be produced. The surplus tritium production remains stored in the moderator zone. Some preliminary calculations illustrating the above concept were carried out and the neutron flux and tritium production distributions are presented. The indications regarding further studies are also suggested. (author)

  12. Four-gate transistor analog multiplier circuit

    Science.gov (United States)

    Mojarradi, Mohammad M. (Inventor); Blalock, Benjamin (Inventor); Cristoloveanu, Sorin (Inventor); Chen, Suheng (Inventor); Akarvardar, Kerem (Inventor)

    2011-01-01

    A differential output analog multiplier circuit utilizing four G.sup.4-FETs, each source connected to a current source. The four G.sup.4-FETs may be grouped into two pairs of two G.sup.4-FETs each, where one pair has its drains connected to a load, and the other par has its drains connected to another load. The differential output voltage is taken at the two loads. In one embodiment, for each G.sup.4-FET, the first and second junction gates are each connected together, where a first input voltage is applied to the front gates of each pair, and a second input voltage is applied to the first junction gates of each pair. Other embodiments are described and claimed.

  13. Dissociative electron attachment to DNA-diamine thin films: Impact of the DNA close environment on the OH{sup −} and O{sup −} decay channels

    Energy Technology Data Exchange (ETDEWEB)

    Boulanouar, Omar; Fromm, Michel; Mavon, Christophe [UMR CNRS 6249 Chrono-Environnement, Laboratoire de Chimie Physique et Rayonnements – Alain Chambaudet, LRC CEA, Université de Franche-Comté, 16 route de Gray, F-25030 Besançon cedex (France); Cloutier, Pierre; Sanche, Léon [Groupe en Sciences des Radiations, Département de Médecine Nucléaire et de Radiobiologie, Faculté de Médecine, Université de Sherbrooke, Québec J1H 5N4 (Canada)

    2013-08-07

    We measure the desorption of anions stimulated by the impact of 0–20 eV electrons on highly uniform thin films of plasmid DNA-diaminopropane. The results are accurately correlated with film thickness and composition by AFM and XPS measurements, respectively. Resonant structures in the H{sup −}, O{sup −}, and OH{sup −} yield functions are attributed to the decay of transient anions into the dissociative electron attachment (DEA) channel. The diamine induces ammonium-phosphate bridges along the DNA backbone, which suppresses the DEA O{sup −} channel and in counter-part increases considerably the desorption of OH{sup −}. The close environment of the phosphate groups may therefore play an important role in modulating the rate and type of DNA damages induced by low energy electrons.

  14. Faster Double-Size Bipartite Multiplication out of Montgomery Multipliers

    Science.gov (United States)

    Yoshino, Masayuki; Okeya, Katsuyuki; Vuillaume, Camille

    This paper proposes novel algorithms for computing double-size modular multiplications with few modulus-dependent precomputations. Low-end devices such as smartcards are usually equipped with hardware Montgomery multipliers. However, due to progresses of mathematical attacks, security institutions such as NIST have steadily demanded longer bit-lengths for public-key cryptography, making the multipliers quickly obsolete. In an attempt to extend the lifespan of such multipliers, double-size techniques compute modular multiplications with twice the bit-length of the multipliers. Techniques are known for extending the bit-length of classical Euclidean multipliers, of Montgomery multipliers and the combination thereof, namely bipartite multipliers. However, unlike classical and bipartite multiplications, Montgomery multiplications involve modulus-dependent precomputations, which amount to a large part of an RSA encryption or signature verification. The proposed double-size technique simulates double-size multiplications based on single-size Montgomery multipliers, and yet precomputations are essentially free: in an 2048-bit RSA encryption or signature verification with public exponent e=216+1, the proposal with a 1024-bit Montgomery multiplier is at least 1.5 times faster than previous double-size Montgomery multiplications.

  15. Efek Multiplier Zakat terhadap Pendapatan di Provinsi DKI Jakarta

    OpenAIRE

    Al Arif, M. Nur Rianto

    2012-01-01

    The aim of this research is to analyse the multiplier effect of zakâh revenue in DKI Jakarta. A study case at Badan Amil Zakat, Infak, and Sadaqah (BAZIS) DKI Jakarta. Least square method is used to analyze the data. The coefficients will be used to calculate the multiplier effect of zakâh-revenue and it will be compared with the economy without zakah revenue. The results showed 2,522 multiplier effects of zakâh-revenue and 3.561 multiplier effect ofeconomic income without zakâh-revenue. Thi...

  16. A study of mini-channel thermal module design for achieving high stability and high capability in electronic cooling

    International Nuclear Information System (INIS)

    Wang, Hsiang-Li; Wu, Huang-Ching; Kong Wang, S.; Hung, Tzu-Chen; Yang, Ruey-Jen

    2013-01-01

    In this study, pressure drop and heat transfer characteristics of multiple-mini-channel thermal modules were investigated quantitatively. The flow channels, which were mounted on one side of a copper test section, were designed in three types: (1) the first module consists of fourteen straight and parallel channels with a rectangular cross section of 1 mm × 3 mm, (2) the second module consists of fourteen gradually widening channels with a U-shaped cross section starting from an inlet section of 0.5 mm × 3 mm and increasing to an outlet section of 1 mm × 3 mm, and (3) the third module is similar to the second module except for the rectangular cross section. Visual observations and the measured boiling curves show that, in the straight channels, some bubbles cannot be flushed out of the channels fast enough, so they tend to flow back and accumulate at the entrance. This results in a rather dry channel condition for CHF (critical heat flux) to occur for the cases with low flow rates. For the widening channel modules, no occurrence of CHF was observed under an even lower operating pressure in an attempt to induce the incipient of CHF. Under a similar temperature rise at the channel exit, the maximum heat removal rate of the widening channels reaches 27 W/cm 2 which is at least twice as high as that of the straight channels. -- Highlights: ► Three mini-channel modules were designed, and experiments were carried out on pressure drop and heat transfer characteristics. ► Comparisons were made between one regular straight-channel module and two widening-channel modules with rectangular and U-shaped cross sections. ► It was found that the widening channels yield a stable two-phase heat transfer mode with no occurrence of CHF due to a better movement of the bubbles and the absence of backflow which causes accumulation of bubbles commonly occur at the entrance of the straight-shaped parallel channels. ► The maximum heat removal rate of the widening channels reaches

  17. Non-local coupled-channels optical calculation of electron scattering by atomic hydrogen at 54.42 eV

    International Nuclear Information System (INIS)

    Ratnavelu, K.; McCarthy, I.E.

    1990-01-01

    The present study incorporates the non-local optical potentials for the continuum within the coupled-channels optical framework to study electron scattering from atomic hydrogen at 54.42 eV. Nine-state coupled-channels calculations with non-local and local continuum optical potentials were performed. The results for differential, total and ionization cross sections as well as the 2p angular correlation parameters λ and R are comparable with other non-perturbative calculations. There are still discrepancies between theory and experiment, particularly for λ and R at larger angles. (author)

  18. Scattering and mobility in indium gallium arsenide channel, pseudomorphic high electron mobility transistors (InGaAs pHEMTs)

    International Nuclear Information System (INIS)

    Pearson, J.L.

    1999-03-01

    Extensive transport measurements have been completed on deep and shallow-channelled InGaAs p-HEMTs of varying growth temperature, indium content, spacer thickness and doping density, with a view to a thorough characterisation, both in the metallic and the localised regimes. Particular emphasis was given to MBE grown layers, with characteristics applicable for device use, but low measurement temperatures were necessary to resolve the elastic scattering mechanisms. Measurements made in the metallic regime included transport and quantum mobility - the former over a range of temperatures between 1.5K to 300K. Conductivity measurements were also acquired in the strong localisation regime between about 1.5K and 100K. Experimentally determined parameters were tested for comparison with those predicted by an electrostatic model. Excellent agreement was obtained for carrier density. Other parameters were less well predicted, but the relevant experimental measurements, including linear depletion of the 2DEG, were sensitive to any excess doping above a 'critical' value determined by the model. At low temperature (1.5K), it was found that in all samples tested, transport mobility was strongly limited at all carrier densities by a large q mechanism, possibly intrinsic to the channel. This was ascribed either to scattering by the long-range potentials arising from the indium concentration fluctuations or fluctuations in the thickness of the channel layer. This mechanism dominates the transport at low carrier densities for all samples, but at high carrier density, an additional mechanism is significant for samples with the thinnest spacers tested (2.5nm). This is ascribed to direct electron interaction with the states of the donor layer, and produces a characteristic transport mobility peak. At higher carrier densities, past the peak, quantum mobility was found only to increase monotonically in value. Remote ionised impurity scattering while significant, particularly for samples

  19. Problems of noise modeling in the presence of total current branching in high electron mobility transistor and field-effect transistor channels

    International Nuclear Information System (INIS)

    Shiktorov, P; Starikov, E; Gružinskis, V; Varani, L; Sabatini, G; Marinchio, H; Reggiani, L

    2009-01-01

    In the framework of analytical and hydrodynamic models for the description of carrier transport and noise in high electron mobility transistor/field-effect transistor channels the main features of the intrinsic noise of transistors are investigated under continuous branching of the current between channel and gate. It is shown that the current-noise and voltage-noise spectra at the transistor terminals contain an excess noise related to thermal excitation of plasma wave modes in the dielectric layer between the channel and gate. It is found that the set of modes of excited plasma waves can be governed by the external embedding circuits, thus violating a universal description of noise in terms of Norton and Thevenin noise generators

  20. Multiplier method may be unreliable to predict the timing of temporary hemiepiphysiodesis for coronal angular deformity.

    Science.gov (United States)

    Wu, Zhenkai; Ding, Jing; Zhao, Dahang; Zhao, Li; Li, Hai; Liu, Jianlin

    2017-07-10

    The multiplier method was introduced by Paley to calculate the timing for temporary hemiepiphysiodesis. However, this method has not been verified in terms of clinical outcome measure. We aimed to (1) predict the rate of angular correction per year (ACPY) at the various corresponding ages by means of multiplier method and verify the reliability based on the data from the published studies and (2) screen out risk factors for deviation of prediction. A comprehensive search was performed in the following electronic databases: Cochrane, PubMed, and EMBASE™. A total of 22 studies met the inclusion criteria. If the actual value of ACPY from the collected date was located out of the range of the predicted value based on the multiplier method, it was considered as the deviation of prediction (DOP). The associations of patient characteristics with DOP were assessed with the use of univariate logistic regression. Only one article was evaluated as moderate evidence; the remaining articles were evaluated as poor quality. The rate of DOP was 31.82%. In the detailed individual data of included studies, the rate of DOP was 55.44%. The multiplier method is not reliable in predicting the timing for temporary hemiepiphysiodesis, even though it is prone to be more reliable for the younger patients with idiopathic genu coronal deformity.

  1. Multipliers for the Absolute Euler Summability of Fourier Series

    Indian Academy of Sciences (India)

    In this paper, the author has investigated necessary and sufficient conditions for the absolute Euler summability of the Fourier series with multipliers. These conditions are weaker than those obtained earlier by some workers. It is further shown that the multipliers are best possible in certain sense.

  2. Multiplier convergent series and uniform convergence of mapping ...

    Indian Academy of Sciences (India)

    MS received 14 April 2011; revised 17 November 2012. Abstract. In this paper, we introduce the frame property of complex sequence sets and study the uniform convergence of nonlinear mapping series in β-dual of spaces consisting of multiplier convergent series. Keywords. Multiplier convergent series; mapping series. 1.

  3. Dimension of the c-nilpotent multiplier of Lie algebras

    Indian Academy of Sciences (India)

    Abstract. The purpose of this paper is to derive some inequalities for dimension of the c-nilpotent multiplier of finite dimensional Lie algebras and their factor Lie algebras. We further obtain an inequality between dimensions of c-nilpotent multiplier of Lie algebra L and tensor product of a central ideal by its abelianized factor ...

  4. Silicon Photo-Multiplier Radiation Hardness Tests with a White Neutron Beam

    International Nuclear Information System (INIS)

    Montanari, A.; Tosi, N.; Pietropaolo, A.; Andreotti, M.; Baldini, W.; Calabrese, R.; Cibinetto, G.; Luppi, E.; Cotta Ramusino, A.; Malaguti, R.; Santoro, V.; Tellarini, G.; Tomassetti, L.; De Donato, C.; Reali, E.

    2013-06-01

    We report radiation hardness tests performed, with a white neutron beam, at the Geel Electron Linear Accelerator in Belgium on silicon Photo-Multipliers. These are semiconductor photon detectors made of a square matrix of Geiger-Mode Avalanche photo-diodes on a silicon substrate. Several samples from different manufacturers have been irradiated integrating up to about 6.2 x 10 9 1-MeV-equivalent neutrons per cm 2 . (authors)

  5. Charge exchange and ionization in atom-multiply-charged ion collisions

    International Nuclear Information System (INIS)

    Presnyakov, L.P.; Uskov, D.B.

    1988-01-01

    This study investigates one-electron transitions to the continuous and discrete spectra induced by a collision of atom A and multiply-charged ion B +Z with nuclear charge Z > 3. An analytical method is developed the charge-exchange reaction; this method is a generalization of the decay model and the approximation of nonadiabatic coupling of two states that are used as limiting cases in the proposed approach

  6. Influence of capture to excited states of multiply charged ion beams colliding with small molecules

    International Nuclear Information System (INIS)

    Montenegro, P; Monti, J M; Fojón, O A; Hanssen, J; Rivarola, R D

    2015-01-01

    Electron capture by multiply charged ions impacting on small molecules is theoretically investigated. Particular attention is paid to the case of biological targets. The interest is focused on the importance of the transition to excited final states which can play a dominant role on the total capture cross sections. Projectiles at intermediate and high collision energies are considered. Comparison with existing experimental data is shown. (paper)

  7. Spatial distribution of ion energy related on electron density in a plasma channel generated in gas clusters by a femtosecond laser

    International Nuclear Information System (INIS)

    Nam, S. M.; Han, J. M.; Cha, Y. H.; Lee, Y. W.; Rhee, Y. J.; Cha, H. K.

    2008-01-01

    Neutron generation through Coulomb explosion of deuterium contained gas clusters is known as one of the very effective methods to produce fusion neutrons using a table top terawatt laser. The energy of ions produced through Coulomb explosions is very important factor to generate neutrons efficiently. Until the ion energy reaches around∼MeV level, the D D fusion reaction probability increases exponentially. The understanding of laser beam propagation and laser energy deposition in clusters is very important to improve neutron yields. As the laser beam propagates through clusters medium, laser energy is absorbed in clusters by ionization of molecules consisting clusters. When the backing pressure of gas increases, the average size of clusters increases and which results in higher energy absorption and earlier termination of laser propagation. We first installed a Michelson interferometer to view laser beam traces in a cluster plume and to measure spatial electron density profiles of a plasma channel which was produced by a laser beam. And then we measured the energy of ions distributed along the plasma channel with a translating slit to select ions from narrow parts of a plasma channel. In our experiments, methane gas was used to produce gas clusters at a room temperature and the energy distribution of proton ions for different gas backing pressure were measured by the time of flight method using dual micro channel plates. By comparing the distribution of ion energies and electron densities, we could understand the condition for effective laser energy delivery to clusters

  8. Optimizing strassen matrix multiply on GPUs

    KAUST Repository

    ul Hasan Khan, Ayaz; Al-Mouhamed, Mayez; Fatayer, Allam

    2015-01-01

    © 2015 IEEE. Many core systems are basically designed for applications having large data parallelism. Strassen Matrix Multiply (MM) can be formulated as a depth first (DFS) traversal of a recursion tree where all cores work in parallel on computing each of the NxN sub-matrices that reduces storage at the detriment of large data motion to gather and aggregate the results. We propose Strassen and Winograd algorithms (S-MM and W-MM) based on three optimizations: a set of basic algebra functions to reduce overhead, invoking efficient library (CUBLAS 5.5), and parameter-tuning of parametric kernel to improve resource occupancy. On GPUs, W-MM and S-MM with one recursion level outperform CUBLAS 5.5 Library with up to twice as faster for large arrays satisfying N>=2048 and N>=3072, respectively. Compared to NVIDIA SDK library, S-MM and W-MM achieved a speedup between 20x to 80x for the above arrays. The proposed approach can be used to enhance the performance of CUBLAS and MKL libraries.

  9. Optimizing strassen matrix multiply on GPUs

    KAUST Repository

    ul Hasan Khan, Ayaz

    2015-06-01

    © 2015 IEEE. Many core systems are basically designed for applications having large data parallelism. Strassen Matrix Multiply (MM) can be formulated as a depth first (DFS) traversal of a recursion tree where all cores work in parallel on computing each of the NxN sub-matrices that reduces storage at the detriment of large data motion to gather and aggregate the results. We propose Strassen and Winograd algorithms (S-MM and W-MM) based on three optimizations: a set of basic algebra functions to reduce overhead, invoking efficient library (CUBLAS 5.5), and parameter-tuning of parametric kernel to improve resource occupancy. On GPUs, W-MM and S-MM with one recursion level outperform CUBLAS 5.5 Library with up to twice as faster for large arrays satisfying N>=2048 and N>=3072, respectively. Compared to NVIDIA SDK library, S-MM and W-MM achieved a speedup between 20x to 80x for the above arrays. The proposed approach can be used to enhance the performance of CUBLAS and MKL libraries.

  10. The Effects of Channel Curvature and Protrusion Height on Nucleate Boiling and the Critical Heat Flux of a Simulated Electronic Chip

    Science.gov (United States)

    1994-05-01

    parameters and geometry factor. 57 3.2 Laminar sublayer and buffer layer thicknesses for geometry of Mudawar and Maddox.ŝ 68 3.3 Correlation constants...transfer from simulated electronic chip heat sources that are flush with the flow channel wall. Mudawar and Maddox2" have studied enhanced surfaces...bias error was not estimated; however, the percentage of heat loss measured compares with that previously reported by Mudawar and Maddox19 for a

  11. Experimental and numerical investigation of flow field and heat transfer from electronic components in a rectangular channel with an impinging jet

    Directory of Open Access Journals (Sweden)

    Calisir Tamer

    2015-01-01

    Full Text Available Thermal control of electronic components is a continuously emerging problem as power loads keep increasing. The present study is mainly focused on experimental and numerical investigation of impinging jet cooling of 18 (3 × 6 array flash mounted electronic components under a constant heat flux condition inside a rectangular channel in which air, following impingement, is forced to exit in a single direction along the channel formed by the jet orifice plate and impingement plate. Copper blocks represent heat dissipating electronic components. Inlet flow velocities to the channel were measured by using a Laser Doppler Anemometer (LDA system. Flow field observations were performed using a Particle Image Velocimetry (PIV and thermocouples were used for temperature measurements. Experiments and simulations were conducted for Re = 4000 – 8000 at fixed value of H = 10 × Dh. Flow field results were presented and heat transfer results were interpreted using the flow measurement observations. Numerical results were validated with experimental data and it was observed that the results are in agreement with the experiments.

  12. Electronic structure of elements and compounds and electronic phases of solids

    International Nuclear Information System (INIS)

    Nadykto, B.A.

    2000-01-01

    The paper reviews technique and computed energies for various electronic states of many-electron multiply charged ions, molecular ions, and electronic phases of solids. The model used allows computation of the state energy for free many-electron multiply charged ions with relative accuracy ∼10 -4 suitable for analysis of spectroscopy data

  13. Lower-Order Compensation Chain Threshold-Reduction Technique for Multi-Stage Voltage Multipliers

    Directory of Open Access Journals (Sweden)

    Francesco Dell’ Anna

    2018-04-01

    Full Text Available This paper presents a novel threshold-compensation technique for multi-stage voltage multipliers employed in low power applications such as passive and autonomous wireless sensing nodes (WSNs powered by energy harvesters. The proposed threshold-reduction technique enables a topological design methodology which, through an optimum control of the trade-off among transistor conductivity and leakage losses, is aimed at maximizing the voltage conversion efficiency (VCE for a given ac input signal and physical chip area occupation. The conducted simulations positively assert the validity of the proposed design methodology, emphasizing the exploitable design space yielded by the transistor connection scheme in the voltage multiplier chain. An experimental validation and comparison of threshold-compensation techniques was performed, adopting 2N5247 N-channel junction field effect transistors (JFETs for the realization of the voltage multiplier prototypes. The attained measurements clearly support the effectiveness of the proposed threshold-reduction approach, which can significantly reduce the chip area occupation for a given target output performance and ac input signal.

  14. Lower-Order Compensation Chain Threshold-Reduction Technique for Multi-Stage Voltage Multipliers.

    Science.gov (United States)

    Dell' Anna, Francesco; Dong, Tao; Li, Ping; Wen, Yumei; Azadmehr, Mehdi; Casu, Mario; Berg, Yngvar

    2018-04-17

    This paper presents a novel threshold-compensation technique for multi-stage voltage multipliers employed in low power applications such as passive and autonomous wireless sensing nodes (WSNs) powered by energy harvesters. The proposed threshold-reduction technique enables a topological design methodology which, through an optimum control of the trade-off among transistor conductivity and leakage losses, is aimed at maximizing the voltage conversion efficiency (VCE) for a given ac input signal and physical chip area occupation. The conducted simulations positively assert the validity of the proposed design methodology, emphasizing the exploitable design space yielded by the transistor connection scheme in the voltage multiplier chain. An experimental validation and comparison of threshold-compensation techniques was performed, adopting 2N5247 N-channel junction field effect transistors (JFETs) for the realization of the voltage multiplier prototypes. The attained measurements clearly support the effectiveness of the proposed threshold-reduction approach, which can significantly reduce the chip area occupation for a given target output performance and ac input signal.

  15. Design and characterization of a 64 channels ASIC front-end electronics for high-flux particle beam detectors

    Science.gov (United States)

    Fausti, F.; Mazza, G.; Attili, A.; Mazinani, M. Fadavi; Giordanengo, S.; Lavagno, M.; Manganaro, L.; Marchetto, F.; Monaco, V.; Sacchi, R.; Vignati, A.; Cirio, R.

    2017-09-01

    A new wide-input range 64-channels current-to-frequency converter ASIC has been developed and characterized for applications in beam monitoring of therapeutic particle beams. This chip, named TERA09, has been designed to extend the input current range, compared to the previous versions of the chip, for dealing with high-flux pulsed beams. A particular care was devoted in achieving a good conversion linearity over a wide bipolar input current range. Using a charge quantum of 200 fC, a linearity within ±2% for an input current range between 3 nA and 12 μA is obtained for individual channels, with a gain spread among the channels of about 3%. By connecting all the 64 channels of the chip to a common input, the current range can be increased 64 times preserving a linearity within ±3% in the range between and 20 μA and 750 μA.

  16. Design of two easily-testable VLSI array multipliers

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, J.; Shen, J.P.

    1983-01-01

    Array multipliers are well-suited to VLSI implementation because of the regularity in their iterative structure. However, most VLSI circuits are very difficult to test. This paper shows that, with appropriate cell design, array multipliers can be designed to be very easily testable. An array multiplier is called c-testable if all its adder cells can be exhaustively tested while requiring only a constant number of test patterns. The testability of two well-known array multiplier structures are studied. The conventional design of the carry-save array multipler is shown to be not c-testable. However, a modified design, using a modified adder cell, is generated and shown to be c-testable and requires only 16 test patterns. Similar results are obtained for the baugh-wooley two's complement array multiplier. A modified design of the baugh-wooley array multiplier is shown to be c-testable and requires 55 test patterns. The implementation of a practical c-testable 16*16 array multiplier is also presented. 10 references.

  17. Analog fourier transform channelizer and OFDM receiver

    OpenAIRE

    2007-01-01

    An OFDM receiver having an analog multiplier based I-Q channelizing filter, samples and holds consecutive analog I-Q samples of an I-Q baseband, the I-Q basebands having OFDM sub-channels. A lattice of analog I-Q multipliers and analog I-Q summers concurrently receives the held analog I-Q samples, performs analog I-Q multiplications and analog I-Q additions to concurrently generate a plurality of analog I-Q output signals, representing an N-point discrete Fourier transform of the held analog ...

  18. Digital predistortion of 75–110 GHz W-band frequency multiplier for fiber wireless short range access systems

    DEFF Research Database (Denmark)

    Zhao, Ying; Deng, Lei; Pang, Xiaodan

    2011-01-01

    be effectively pre-compensated. Without using costly W-band components, a transmission system with 26km fiber and 4m wireless transmission operating at 99.6GHz is experimentally validated. Adjacent-channel power ratio (ACPR) improvements for IQ-modulated vector signals are guaranteed and transmission......We present a W-band fiber-wireless transmission system based on a nonlinear frequency multiplier for high-speed wireless short range access applications. By implementing a baseband digital signal predistortion scheme, intensive nonlinear distortions induced in a sextuple frequency multiplier can...... performances for fiber and wireless channels are studied. This W-band predistortion technique is a promising candidate for applications in high capacity wireless-fiber access systems....

  19. Citizens and service channels: channel choice and channel management implications

    NARCIS (Netherlands)

    Pieterson, Willem Jan

    2010-01-01

    The arrival of electronic channels in the 1990s has had a huge impact on governmental service delivery. The new channels have led to many new opportunities to improve public service delivery, not only in terms of citizen satisfaction, but also in cost reduction for governmental agencies. However,

  20. Decrease in effective electron mobility in the channel of a metal-oxide-semiconductor transistor as the gate length is decreased

    International Nuclear Information System (INIS)

    Frantsuzov, A. A.; Boyarkina, N. I.; Popov, V. P.

    2008-01-01

    Effective electron mobility μ eff in channels of metal-oxide-semiconductor transistors with a gate length L in the range of 3.8 to 0.34 μm was measured; the transistors were formed on wafers of the silicon-oninsulator type. It was found that μ eff decreases as L is decreased. It is shown that this decrease can be accounted for by the effect of series resistances of the source and drain only if it is assumed that there is a rapid increase in these resistances as the gate voltage is decreased. This assumption is difficult to substantiate. A more realistic model is suggested; this model accounts for the observed decrease in μ eff as L is decreased. The model implies that zones with a mobility lower than that in the middle part of the channel originate at the edges of the gate. An analysis shows that, in this case, the plot of the dependence of 1/μ eff on 1/L should be linear, which is exactly what is observed experimentally. The use of this plot makes it possible to determine both the electron mobility μ 0 in the middle part of the channel and the quantity A that characterizes the zones with lowered mobility at the gate’s edges.

  1. Towards a measurement of the W-boson inclusive production cross section in the electron-neutrino channel in the Atlas experiment at LHC

    International Nuclear Information System (INIS)

    Guillemin, Th.

    2009-06-01

    The charged W-boson will be abundantly produced at the Large Hadron Collider (LHC) in proton-proton collisions at a center-of-mass energy of 14 TeV: its frequency production is about 1 Hz at low luminosity. Its decay in the electron channel will have a clear signature in the ATLAS detector, defined by a high transverse momentum electron and a high missing transverse energy. The ATLAS detector is a multi-purposes detector made up of a tracker, an electromagnetic calorimeter, a hadronic calorimeter and a muon spectrometer. It is fully installed in its cavern and recorded data with the first LHC beam in September 2008. A first part of the thesis presents a full analysis strategy for the W-boson inclusive production cross section with the first ATLAS data, maximizing the inputs from real data with respect to simulated ones. The main contributions to the systematical uncertainty are identified and estimated: a measurement precision better than 10% will be reachable from the first phase of the experiment. A second part is dedicated to the time alignment of the liquid argon calorimeters readout channels, a required step to reach the nominal performances. Timing constants are computed from the data recorded in September 2008: they will allow a time alignment of all channels at a 2-3 ns level for the start-up. (author)

  2. Analytical theory of frequency-multiplying gyro-traveling-wave-tubes

    International Nuclear Information System (INIS)

    Nusinovich, G.S.; Chen, W.; Granatstein, V.L.

    2001-01-01

    The theory is developed which describes analytically the gain and bandwidth in frequency-multiplying gyro-traveling-wave-tubes. In this theory the input waveguide is considered in the small-signal approximation. Then, in the drift region separating the input and output waveguides, the electron ballistic bunching evolves which causes the appearance in the electron current density of the harmonics of the signal frequency. The excitation of the output waveguide by one of these harmonics is considered in a specified current approximation. This makes the analytical study of a large-signal operation possible. The theory is illustrated by using it to analyze the performance of an existing experimental tube

  3. Confinement of multiply charged ions in an ECRH mirror plasma

    International Nuclear Information System (INIS)

    Petty, C.C.

    1989-06-01

    This thesis is an experimental study of multiply charged ions in the Constance B mirror experiment. By measuring the ion densities, end loss fluxes and ion temperatures, the parallel confinement times for the first five charge states of oxygen and neon plasmas are determined. The parallel ion confinement times increase with charge state and peak on axis, both indications of an ion-confining potential dip created by the hot electrons. The radial profile of ion end loss is usually hollow due to large ion radial transport (τ paralleli ∼ τ perpendiculari ), with the peak fluxes occurring at the edge of the electron cyclotron resonance zone. Several attempts are made to increase the end loss of selected ion species. Using minority ICRH, the end loss flux of resonant ions increases by 20% in cases when radial transport induced by ICRH is not too severe. A large antenna voltage can also extinguish the plasma. By adding helium to an oxygen plasma, the end loss of O 6+ increases by 80% due to decreased ion radial transport. An ion model is developed to predict the ion densities, end loss fluxes and confinement times in the plasma center using the ion particle balance equations, the quasineutrality condition and theoretical confinement time formulas. The model generally agrees with the experimental data for oxygen and neon plasmas to within experimental error. Under certain conditions spatial diffusion appears to determine the parallel ion confinement time of the highest charge states. For oxygen plasmas during ICRH, the measured parallel confinement time of the resonant ions is much shorter than their theoretical value, probably due to rf diffusion of the ions into the loss cone. 58 refs., 101 figs., 16 tabs

  4. 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).

  5. Photoionization of multiply charged ions at the advanced light source

    International Nuclear Information System (INIS)

    Schlachter, A.S.; Kilcoyne, A.L.D.; Aguilar, A.; Gharaibeh, M.F.; Emmons, E.D.; Scully, S.W.J.; Phaneuf, R.A.; Muller, A.; Schippers, S.; Alvarez, I.; Cisneros, C.; Hinojosa, G.; McLaughlin, B.M.

    2004-01-01

    Photoionization of multiply charged ions is studied using the merged-beams technique at the Advanced Light Source. Absolute photoionization cross sections have been measured for a variety of ions along both isoelectronic and isonuclear sequences

  6. Cavallo's multiplier for in situ generation of high voltage

    Science.gov (United States)

    Clayton, S. M.; Ito, T. M.; Ramsey, J. C.; Wei, W.; Blatnik, M. A.; Filippone, B. W.; Seidel, G. M.

    2018-05-01

    A classic electrostatic induction machine, Cavallo's multiplier, is suggested for in situ production of very high voltage in cryogenic environments. The device is suitable for generating a large electrostatic field under conditions of very small load current. Operation of the Cavallo multiplier is analyzed, with quantitative description in terms of mutual capacitances between electrodes in the system. A demonstration apparatus was constructed, and measured voltages are compared to predictions based on measured capacitances in the system. The simplicity of the Cavallo multiplier makes it amenable to electrostatic analysis using finite element software, and electrode shapes can be optimized to take advantage of a high dielectric strength medium such as liquid helium. A design study is presented for a Cavallo multiplier in a large-scale, cryogenic experiment to measure the neutron electric dipole moment.

  7. Sociophysics of sexism: normal and anomalous petrie multipliers

    Science.gov (United States)

    Eliazar, Iddo

    2015-07-01

    A recent mathematical model by Karen Petrie explains how sexism towards women can arise in organizations where male and female are equally sexist. Indeed, the Petrie model predicts that such sexism will emerge whenever there is a male majority, and quantifies this majority bias by the ‘Petrie multiplier’: the square of the male/female ratio. In this paper—emulating the shift from ‘normal’ to ‘anomalous’ diffusion—we generalize the Petrie model to a stochastic Poisson model that accommodates heterogeneously sexist men and woman, and that extends the ‘normal’ quadratic Petrie multiplier to ‘anomalous’ non-quadratic multipliers. The Petrie multipliers span a full spectrum of behaviors which we classify into four universal types. A variation of the stochastic Poisson model and its Petrie multipliers is further applied to the context of cyber warfare.

  8. Atomic collisions in fusion plasmas involving multiply charged ions

    International Nuclear Information System (INIS)

    Salzborn, E.

    1980-01-01

    A short survey is given on atomic collisions involving multiply charged ions. The basic features of charge transfer processes in ion-ion and ion-atom collisions relevant to fusion plasmas are discussed. (author)

  9. Efek Multiplier Zakat Terhadap Pendapatan di Propinsi DKI Jakarta

    Directory of Open Access Journals (Sweden)

    M. Nur Rianto Al Arif

    2015-10-01

    Full Text Available The aim of this research is to analyze the multiplier effect of zakah revenue in DKI Jakarta, a study case at Badan Amil Zakat, Infak, and Shadaqah (BAZIS DKI Jakarta. Least square methods is used to analyze the data. The coefficient will be used to calculate the multiplier effect of zakah revenue and it will be compared with the economy without zakah revenue. The result showed 2,522 multiplier effects of zakah revenue and 3,561 multiplier effect of economic income without zakah revenue. This suggest that the management of zakah in BAZIS DKI Jakarta still can have a significant influence on the economyDOI: 10.15408/aiq.v4i1.2079

  10. Multiplier less high-speed squaring circuit for binary numbers

    Science.gov (United States)

    Sethi, Kabiraj; Panda, Rutuparna

    2015-03-01

    The squaring operation is important in many applications in signal processing, cryptography etc. In general, squaring circuits reported in the literature use fast multipliers. A novel idea of a squaring circuit without using multipliers is proposed in this paper. Ancient Indian method used for squaring decimal numbers is extended here for binary numbers. The key to our success is that no multiplier is used. Instead, one squaring circuit is used. The hardware architecture of the proposed squaring circuit is presented. The design is coded in VHDL and synthesised and simulated in Xilinx ISE Design Suite 10.1 (Xilinx Inc., San Jose, CA, USA). It is implemented in Xilinx Vertex 4vls15sf363-12 device (Xilinx Inc.). The results in terms of time delay and area is compared with both modified Booth's algorithm and squaring circuit using Vedic multipliers. Our proposed squaring circuit seems to have better performance in terms of both speed and area.

  11. Instructional Computing Project Uses "Multiplier Effect" to Train Florida Teachers.

    Science.gov (United States)

    Roblyer, M. D.; Castine, W. H.

    1987-01-01

    Reviews the efforts undertaken in the Florida Model Microcomputer Trainer Project (FMMTP) and its statewide impact. Outlines its procedural strategies, trainer curriculum, networking system, and the results of its multiplier effect. (ML)

  12. EFEK MULTIPLIER ZAKAT TERHADAP PENDAPATAN DI PROVINSI DKI JAKARTA

    Directory of Open Access Journals (Sweden)

    M. Nur Rianto Al Arif

    2016-02-01

    Full Text Available The aim of this research is to analyse the multiplier effect of zakâh revenue in DKI Jakarta. A study case at Badan Amil Zakat, Infak, and Sadaqah (BAZIS DKI Jakarta. Least square method is used to analyze the data. The coefficients will be used to calculate the multiplier effect of zakâh-revenue and it will  be compared with the economy without zakah revenue. The results showed 2,522 multiplier effects of zakâh-revenue and 3.561 multiplier effect ofeconomic income without zakâh-revenue. This suggests that the management of zakat in BAZIS Jakarta still can have a significant influence on the economy.DOI: 10.15408/aiq.v4i1.2533

  13. Temperature gradient scale length measurement: A high accuracy application of electron cyclotron emission without calibration

    Energy Technology Data Exchange (ETDEWEB)

    Houshmandyar, S., E-mail: houshmandyar@austin.utexas.edu; Phillips, P. E.; Rowan, W. L. [Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (United States); Yang, Z. J. [Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Hubbard, A. E.; Rice, J. E.; Hughes, J. W.; Wolfe, S. M. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02129 (United States)

    2016-11-15

    Calibration is a crucial procedure in electron temperature (T{sub e}) inference from a typical electron cyclotron emission (ECE) diagnostic on tokamaks. Although the calibration provides an important multiplying factor for an individual ECE channel, the parameter ΔT{sub e}/T{sub e} is independent of any calibration. Since an ECE channel measures the cyclotron emission for a particular flux surface, a non-perturbing change in toroidal magnetic field changes the view of that channel. Hence the calibration-free parameter is a measure of T{sub e} gradient. B{sub T}-jog technique is presented here which employs the parameter and the raw ECE signals for direct measurement of electron temperature gradient scale length.

  14. The generalization of the Schur multipliers of Bieberbach groups

    Science.gov (United States)

    Masri, Rohaidah; Hassim, Hazzirah Izzati Mat; Sarmin, Nor Haniza; Ali, Nor Muhainiah Mohd; Idrus, Nor'ashiqin Mohd

    2014-12-01

    The Schur multiplier is the second homology group of a group. It has been found to be isomorphic to the kernel of a homomorphism which maps the elements in the exterior square of the group to the elements in its derived subgroup. Meanwhile, a Bieberbach group is a space group which is a discrete cocompact group of isometries of oriented Euclidean space. In this research, the Schur multipliers of Bieberbach groups with cyclic point group of order two of finite dimension are computed.

  15. Physics of subcritical multiplying regions and experimental validation

    International Nuclear Information System (INIS)

    Salvatores, M.

    1996-01-01

    The coupling of a particle accelerator with a spallation target and with a subcritical multiplying region has been proposed in the fifties and is called here a hybrid system. This article gives some ideas about the energetic balance of such a system. The possibilities of experimental validation of some properties of a subcritical multiplying region by using MASURCA facility at CEA-Cadarache are examined. The results of a preliminary experiment called MUSE are presented. (A.C.)

  16. Isometric multipliers of a vector valued Beurling algebra on a ...

    Indian Academy of Sciences (India)

    Throughout, let S be a nonunital faith- ful abelian semigroup, and let A be a commutative Banach algebra. A map σ : S → S is a multiplier [1, 4] if σ(xy) = xσ(y) = σ(x)y, x,y ∈ S. Let M(S) be the set of all multipliers of S. Then M(S) is a unital abelian semigroup under composition. Since S is faithful, S can be imbedded as an ...

  17. Measurement of the Z boson differential cross-section in transverse momentum in the electron-positron channel with the ATLAS detector at LHC

    International Nuclear Information System (INIS)

    Martinez, Homero

    2013-01-01

    This work presents the measurement of the Z boson differential cross section in transverse momentum (p T Z ), in the electron-positron decay channel, using the ATLAS detector at the LHC. The measurement is done using 4.64 fb -1 of proton-proton collision data, collected in 2011 at a center-of-mass energy of 7 TeV. The result is combined with an independent measurement done in the muon-anti-muon decay channel. The measurement is done up to p T Z = 800 GeV, and has a typical uncertainty of 0.5 % for transverse momentum below 60 GeV, rising up to 5 % towards the end of the spectrum. The measurement is compared to theoretical models and Monte Carlo generators predictions. (author) [fr

  18. Effect of nano-scale morphology on micro-channel wall surface and electrical characterization in lead silicate glass micro-channel plate

    Science.gov (United States)

    Cai, Hua; Li, Fangjun; Xu, Yanglei; Bo, Tiezhu; Zhou, Dongzhan; Lian, Jiao; Li, Qing; Cao, Zhenbo; Xu, Tao; Wang, Caili; Liu, Hui; Li, Guoen; Jia, Jinsheng

    2017-10-01

    Micro-channel plate (MCP) is a two dimensional arrays of microscopic channel charge particle multiplier. Silicate composition and hydrogen reduction are keys to determine surface morphology of micro-channel wall in MCP. In this paper, lead silicate glass micro-channel plates in two different cesium contents (0at%, 0.5at%) and two different hydrogen reduction temperatures (400°C,450°C) were present. The nano-scale morphology, elements content and chemical states of microporous wall surface treated under different alkaline compositions and reduction conditions was investigated by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS), respectively. Meanwhile, the electrical characterizations of MCP, including the bulk resistance, electron gain and the density of dark current, were measured in a Vacuum Photoelectron Imaging Test Facility (VPIT).The results indicated that the granular phase occurred on the surface of microporous wall and diffuses in bulk glass is an aggregate of Pb atom derived from the reduction of Pb2+. In micro-channel plate, the electron gain and bulk resistance were mainly correlated to particle size and distribution, the density of dark current (DDC) went up with the increasing root-mean-square roughness (RMS) on the microporous wall surface. Adding cesiums improved the size of Pb atomic aggregation, lowered the relative concentration of [Pb] reduced from Pb2+ and decreased the total roughness of micro-channel wall surface, leading a higher bulk resistance, a lower electron gain and a less dark current. Increasing hydrogen reduction temperature also improved the size of Pb atomic aggregation, but enhanced the relative concentration of [Pb] and enlarged the total roughness of micro-channel wall surface, leading a higher bulk resistance, a lower electron gain and a larger dark current. The reasons for the difference of electrical characteristics were discussed.

  19. Cluster-assistant generation of multiply charged atomic ions in nanosecond laser ionization of seeded methyl iodide beam

    International Nuclear Information System (INIS)

    Luo Xiaolin; Niu Dongmei; Kong Xianglei; Wen Lihua; Liang Feng; Pei Kemei; Wang Bin; Li Haiyang

    2005-01-01

    The photoionization of methyl iodide beam seeded in argon and helium is studied by time-of-flight mass spectrometry using a 25 ns, 532 nm Nd-YAG laser with intensities in the range of 2 x 10 10 -2 x 10 11 W/cm 2 . Multiply charged ions of I q+ (q = 2-3) and C 2+ with tens of eV kinetic energies have been observed when laser interacts with the middle part of the pulsed molecular beam, whose peak profiles are independent on the laser polarization directions. Strong evidences show that these ions are coming from the Coulomb explosion of multiply charged CH 3 I clusters, and laser induced inverse bremsstrahlung absorption of caged electrons plays a key role in the formation of multiply charged ions

  20. Experiment study on the thick GEM-like multiplier for X-ray photoelectrons energy deposition gaining

    International Nuclear Information System (INIS)

    Zhu Pengfei; Ye Yan; Long Yan; Cao Ningxiang; Jia Xing; Li Jianfeng

    2009-01-01

    The GEM is a novel detector with high gain,high time and location resolution. Imitating the structure of the GEM, a thick GEM-like multiplier which has the similar function with that of the GEM is designed and manufactured. The characteristics of the thick GEM-like multiplier increasing electron energy deposition in absorbing medium has been experimentally studied. The results indicate that the energy deposition gain of x-ray photoelectron in medium is apparent, and the maximum energy deposition can increase by more than 40%. Some suggestions of further increasing the energy deposition are given, and the future application of the way of increasing the x-ray photoelectron energy deposition by the thick GEM-like multiplier in hard x-ray imaging is prospected. (authors)

  1. Single-top production t-channel cross section measurement in the electron+jets final state at ATLAS with 35 pb{sup -1}of data

    Energy Technology Data Exchange (ETDEWEB)

    Khoriauli, Gia

    2012-07-15

    The cross section of the Standard Model electroweak production of a single top quark in the t-channel has been measured using the LHC proton-proton collision data at {radical}(s)=7 TeV, 35 pb{sup -1} of integrated luminosity, recorded by the ATLAS detector during the year 2010. The measurement has been based on a selection of the collision events with an electron and one b-tagged hadronic jet in the central region of the detector and one extra jet in the forward region of the detector. These requirements are dictated by the topology of the final state particles in the t-channel process. They helped to optimize an expected fraction of the t-channel process, according to a study based on Monte-Carlo simulation, in the selected events and suppress the contribution of the background processes. The main background processes such as production of hadronic jets via the strong interaction and production of a single W boson with associated hadronic jets are measured by means of data driven methods developed in this work. The measured cross section of single top quark production in the t-channel process is 59{sup +44}{sub -39}(stat.){sup +63}{sub -39}(syst.) pb. The measured upper limit on the cross section is 226 pb at the 95% confidence level. The results are in agreement with the latest theoretical prediction of the t-channel cross section of the Standard Model production of a single top quark calculated at NNLO, 64.6{sup +3.3}{sub -2.6} pb, considering m {sub t-quark}=172.5 GeV.

  2. Single-top production t-channel cross section measurement in the electron+jets final state at ATLAS with 35 pb-1of data

    International Nuclear Information System (INIS)

    Khoriauli, Gia

    2012-07-01

    The cross section of the Standard Model electroweak production of a single top quark in the t-channel has been measured using the LHC proton-proton collision data at √(s)=7 TeV, 35 pb -1 of integrated luminosity, recorded by the ATLAS detector during the year 2010. The measurement has been based on a selection of the collision events with an electron and one b-tagged hadronic jet in the central region of the detector and one extra jet in the forward region of the detector. These requirements are dictated by the topology of the final state particles in the t-channel process. They helped to optimize an expected fraction of the t-channel process, according to a study based on Monte-Carlo simulation, in the selected events and suppress the contribution of the background processes. The main background processes such as production of hadronic jets via the strong interaction and production of a single W boson with associated hadronic jets are measured by means of data driven methods developed in this work. The measured cross section of single top quark production in the t-channel process is 59 +44 -39 (stat.) +63 -39 (syst.) pb. The measured upper limit on the cross section is 226 pb at the 95% confidence level. The results are in agreement with the latest theoretical prediction of the t-channel cross section of the Standard Model production of a single top quark calculated at NNLO, 64.6 +3.3 -2.6 pb, considering m t-quark =172.5 GeV.

  3. First direct electron microscopic visualization of a tight spatial coupling between GABAA-receptors and voltage-sensitive calcium channels

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Belhage, B; Schousboe, A

    1992-01-01

    Using cerebellar granule neurons in culture it was demonstrated that exposure of the cells to the GABAA receptor agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) leads to an increase in the number of voltage-gated calcium channels as revealed by quantitative preembedding indirect imm...

  4. Orientation-Dependent Electronic Structures and Charge Transport Mechanisms in Ultrathin Polymeric n-Channel Field-Effect Transistors

    NARCIS (Netherlands)

    Fabiano, Simone; Yoshida, Hiroyuki; Chen, Zhihua; Facchetti, Antonio; Loi, Maria Antonietta

    2013-01-01

    We investigated the role of metal/organic semiconductor interface morphology on the charge transport mechanisms and energy level alignment of the n-channel semiconductor poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P-(NDI2ODT2)).

  5. Radiation emission at channeling of electrons in a strained layer Si1-xGex undulator crystal

    DEFF Research Database (Denmark)

    Backe, H.; Krambrich, D.; Lauth, W.

    2013-01-01

    ML source. Spectra taken at the beam energy of 270 MeV at channeling in the undulating (110) planes exhibit a broad excess yield around the theoretically expected photon energies of 0.069 MeV, as compared with a flat silicon reference crystal. Model calculations on the basis of synchrotron-like radiation...

  6. Excitation of half-integer up-shifted decay channel and quasi-mode in plasma edge for high power electron Bernstein wave heating scenario

    Directory of Open Access Journals (Sweden)

    M. Ali Asgarian

    2018-04-01

    Full Text Available Electron Bernstein waves (EBW consist of promising tools in driving localized off-axis current needed for sustained operation as well as effective selective heating scenarios in advanced over dense fusion plasmas like spherical tori and stellarators by applying high power radio frequency waves within the range of Megawatts. Here some serious non-linear effects like parametric decay modes are highly expect-able which have been extensively studied theoretically and experimentally. In general, the decay of an EBW depends on the ratio of the incident frequency and electron cyclotron frequency. At ratios less than two, parametric decay leads to a lower hybrid wave (or an ion Bernstein wave and EBWs at a lower frequency. For ratios more than two, the daughter waves constitute either an electron cyclotron quasi-mode and another EBW or an ion wave and EBW. However, in contrast with these decay patterns, the excitation of an unusual up-shifted frequency decay channel for the ratio less than two is demonstrated in this study which is totally different as to its generation and persistence. It is shown that this mode varies from the conventional parametric decay channels which necessarily satisfy the matching conditions in frequency and wave-vector. Moreover, the excitation of some less-known local non-propagating quasi-modes (virtual modes through weak-turbulence theory and their contributions to energy leakage from conversion process leading the reduction in conversion efficiency is assessed.

  7. Excitation of half-integer up-shifted decay channel and quasi-mode in plasma edge for high power electron Bernstein wave heating scenario

    Science.gov (United States)

    Ali Asgarian, M.; Abbasi, M.

    2018-04-01

    Electron Bernstein waves (EBW) consist of promising tools in driving localized off-axis current needed for sustained operation as well as effective selective heating scenarios in advanced over dense fusion plasmas like spherical tori and stellarators by applying high power radio frequency waves within the range of Megawatts. Here some serious non-linear effects like parametric decay modes are highly expect-able which have been extensively studied theoretically and experimentally. In general, the decay of an EBW depends on the ratio of the incident frequency and electron cyclotron frequency. At ratios less than two, parametric decay leads to a lower hybrid wave (or an ion Bernstein wave) and EBWs at a lower frequency. For ratios more than two, the daughter waves constitute either an electron cyclotron quasi-mode and another EBW or an ion wave and EBW. However, in contrast with these decay patterns, the excitation of an unusual up-shifted frequency decay channel for the ratio less than two is demonstrated in this study which is totally different as to its generation and persistence. It is shown that this mode varies from the conventional parametric decay channels which necessarily satisfy the matching conditions in frequency and wave-vector. Moreover, the excitation of some less-known local non-propagating quasi-modes (virtual modes) through weak-turbulence theory and their contributions to energy leakage from conversion process leading the reduction in conversion efficiency is assessed.

  8. Ultrafast chemical interface scattering as an additional decay channel for nascent nonthermal electrons in small metal nanoparticles.

    Science.gov (United States)

    Bauer, Christophe; Abid, Jean-Pierre; Fermin, David; Girault, Hubert H

    2004-05-15

    The use of 4.2 nm gold nanoparticles wrapped in an adsorbates shell and embedded in a TiO2 metal oxide matrix gives the opportunity to investigate ultrafast electron-electron scattering dynamics in combination with electronic surface phenomena via the surface plasmon lifetimes. These gold nanoparticles (NPs) exhibit a large nonclassical broadening of the surface plasmon band, which is attributed to a chemical interface damping. The acceleration of the loss of surface plasmon phase coherence indicates that the energy and the momentum of the collective electrons can be dissipated into electronic affinity levels of adsorbates. As a result of the preparation process, gold NPs are wrapped in a shell of sulfate compounds that gives rise to a large density of interfacial molecules confined between Au and TiO2, as revealed by Fourier-transform-infrared spectroscopy. A detailed analysis of the transient absorption spectra obtained by broadband femtosecond transient absorption spectroscopy allows separating electron-electron and electron-phonon interaction. Internal thermalization times (electron-electron scattering) are determined by probing the decay of nascent nonthermal electrons (NNEs) and the build-up of the Fermi-Dirac electron distribution, giving time constants of 540 to 760 fs at 0.42 and 0.34 eV from the Fermi level, respectively. Comparison with literature data reveals that lifetimes of NNEs measured for these small gold NPs are more than four times longer than for silver NPs with similar sizes. The surprisingly long internal thermalization time is attributed to an additional decay mechanism (besides the classical e-e scattering) for the energy loss of NNEs, identified as the ultrafast chemical interface scattering process. NNEs experience an inelastic resonant scattering process into unoccupied electronic states of adsorbates, that directly act as an efficient heat bath, via the excitation of molecular vibrational modes. The two-temperature model is no longer

  9. Electron transfer and decay processes of highly charged iodine ions

    International Nuclear Information System (INIS)

    Sakaue, Hiroyuki A.; Danjo, Atsunori; Hosaka, Kazumoto

    2005-01-01

    In the present experimental work we have investigated multi-electron transfer processes in I q+ (q=10, 15, 20 and 25) + Ne, Ar, Kr and Xe collisions at 1.5q keV energy. The branching ratios between Auger and radiative decay channels have been measured in decay processes of multiply excited states formed by multi-electron transfer collisions. It has been shown that, in all the multi-electron transfer processes investigated, the Auger decays are far dominant over the radiative decay processes and the branching ratios are clearly characterized by the average principal quantum number of the initial excited states of projectile ions. We could express the branching ratios in high Rydberg states formed in multi-electron transfer processes by using the decay probability of one Auger electron emission. (author)

  10. Modeling Photo-multiplier Gain and Regenerating Pulse Height Data for Application Development

    Science.gov (United States)

    Aspinall, Michael D.; Jones, Ashley R.

    2018-01-01

    Systems that adopt organic scintillation detector arrays often require a calibration process prior to the intended measurement campaign to correct for significant performance variances between detectors within the array. These differences exist because of low tolerances associated with photo-multiplier tube technology and environmental influences. Differences in detector response can be corrected for by adjusting the supplied photo-multiplier tube voltage to control its gain and the effect that this has on the pulse height spectra from a gamma-only calibration source with a defined photo-peak. Automated methods that analyze these spectra and adjust the photo-multiplier tube bias accordingly are emerging for hardware that integrate acquisition electronics and high voltage control. However, development of such algorithms require access to the hardware, multiple detectors and calibration source for prolonged periods, all with associated constraints and risks. In this work, we report on a software function and related models developed to rescale and regenerate pulse height data acquired from a single scintillation detector. Such a function could be used to generate significant and varied pulse height data that can be used to integration-test algorithms that are capable of automatically response matching multiple detectors using pulse height spectra analysis. Furthermore, a function of this sort removes the dependence on multiple detectors, digital analyzers and calibration source. Results show a good match between the real and regenerated pulse height data. The function has also been used successfully to develop auto-calibration algorithms.

  11. Low-order-mode harmonic multiplying gyrotron traveling-wave amplifier in W band

    International Nuclear Information System (INIS)

    Yeh, Y. S.; Chen, C. H.; Yang, S. J.; Lai, C. H.; Lin, T. Y.; Lo, Y. C.; Hong, J. W.; Hung, C. L.; Chang, T. H.

    2012-01-01

    Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) allow for magnetic field reduction and frequency multiplication. To avoid absolute instabilities, this work proposes a W-band harmonic multiplying gyro-TWA operating at low-order modes. By amplifying a fundamental harmonic TE 11 drive wave, the second harmonic component of the beam current initiates a TE 21 wave to be amplified. Absolute instabilities in the gyro-TWA are suppressed by shortening the interaction circuit and increasing wall losses. Simulation results reveal that compared with Ka-band gyro-TWTs, the lower wall losses effectively suppress absolute instabilities in the W-band gyro-TWA. However, a global reflective oscillation occurs as the wall losses decrease. Increasing the length or resistivity of the lossy section can reduce the feedback of the oscillation to stabilize the amplifier. The W-band harmonic multiplying gyro-TWA is predicted to yield a peak output power of 111 kW at 98 GHz with an efficiency of 25%, a saturated gain of 26 dB, and a bandwidth of 1.6 GHz for a 60 kV, 7.5 A electron beam with an axial velocity spread of 8%.

  12. Reverse electron flow-induced ROS production is attenuated by activation of mitochondrial Ca2+-sensitive K+ channels

    NARCIS (Netherlands)

    Heinen, André; Aldakkak, Mohammed; Stowe, David F.; Rhodes, Samhita S.; Riess, Matthias L.; Varadarajan, Srinivasan G.; Camara, Amadou K. S.

    2007-01-01

    Mitochondria generate reactive oxygen species (ROS) dependent on substrate conditions, O(2) concentration, redox state, and activity of the mitochondrial complexes. It is well known that the FADH(2)-linked substrate succinate induces reverse electron flow to complex I of the electron transport chain

  13. Analysis of defect structures in recrystallized amorphous layers of self-ion irradiated silicon by channeling and transmission electron microscopy measurements

    International Nuclear Information System (INIS)

    Pronko, P.P.; Rechtin, M.D.; Foti, G.; Csepregi, L.; Kennedy, E.F.; Mayer, J.W.

    1976-01-01

    The dominant defect structures in these reordered layers have been identified as twins whose dimensions change in size going from the surface to the interface. A high density of clustered defects is observed near the interface and is manifested by the presence of a heavy strain contrast in the electron micrograph image. Some fine polycrystallinity is also observed in the region of the interface between the regrown layer and the substrate. The 2 MeV 4 He channeling results indicate that, in this kind of defect arrangement, the standard analysis for reducing the channeling data cannot be applied. A more direct way to examine the depth dependence of the defect distribution by channeling is to follow the change in the minimum yield as a function of layer removal. The results obtained in this way show that the number of scattering centers (N/sub D//N/sub O/) is approximately constant in the first 3000 A and increases very fast near the interface. No tail in the scattering distribution is observed to penetrate the substrate when using the stripping procedure. This agrees generally with the TEM results

  14. Kinetic description of self-field effects on laser and betatron emission in wiggler-pumped ion-channel free electron lasers

    International Nuclear Information System (INIS)

    Alimohamadi, M; Mehdian, H; Hasanbeigi, A

    2011-01-01

    The effects of self-fields on the free electron lasers (FELs) with a helical wiggler and ion-channel guiding are considered. The steady-state orbits for a single electron in this configuration are obtained. The rate of change of axial velocity with energy, the characteristic function Φ, is derived and studied numerically. A kinetic approach has been used to get the effects of self-field on the FEL and betatron gain formula in the low-gain-pre-pass limit. It is shown that betatron gain is smaller than FEL gain. We also found a gain decrement (enhancement), arising from diamagnetism (paramagnetism) generated by the self-magnetic field for group I (group II) orbits. It is interesting that the gain enhancement is found for the non-relativistic part of group II orbits. The FEL gain and betatron gain have also been investigated for different relativistic factors γ.

  15. A convergent-beam electron diffraction study of strain homogeneity in severely strained aluminum processed by equal-channel angular pressing

    Energy Technology Data Exchange (ETDEWEB)

    Alhajeri, Saleh N. [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Department of Manufacturing Engineering, College of Technological Studies, PAAET, PO Box 42325, Shuwaikh 70654 (Kuwait); Fox, Alan G. [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Mechanical Engineering Department, Asian University, 89 Moo 12, Highway 331, Banglamung, Chon Buri 20260 (Thailand); Langdon, Terence G., E-mail: langdon@usc.edu [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Departments of Aerospace and Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States)

    2011-11-15

    Aluminum of commercial purity was processed by equal-channel angular pressing (ECAP) through two, four and eight passes at room temperature. A series of [1 1 4] convergent-beam electron diffraction (CBED) zone axis patterns were obtained using an electron probe with a diameter of 20 nm. Observations were recorded both immediately adjacent to the grain boundaries and in the grain interiors. Symmetry breaking of the higher-order Laue zone (HOLZ) lines was observed adjacent to the boundaries after two and four passes but not in the grain interiors. Pattern simulation of the CBED patterns taken from the two- and four-pass samples adjacent to the boundaries revealed a homogeneous strain with compressive and shear components. The presence of these homogeneous strains demonstrates that the internal stresses associated with the deformation of aluminum at room temperature are localized in the close vicinity, to within {approx}20 nm, of the grain boundaries.

  16. Investigation of planar channeling radiation on diamond and quartz crystals at electron energies between 14 and 34 MeV and probing the influence of ultrasonic waves on channeling radiation

    International Nuclear Information System (INIS)

    Azadegan, B.

    2007-01-01

    Measurements of planar channeling radiation (CR) have been performed at the electron beam of ELBE within an energy range between 14 and 34 MeV and for thicknesses of the diamond crystals between 42.5 and 500 μm. Absolute CR photon yields have for the first time been obtained for the above given ranges of electron energy and crystal thickness. The square-root dependence of the planar CR photon yield on the thickness of diamond crystals has been confirmed. A systematic quantitative investigation of the influence of the crystal thickness on the CR line shape has for the first time been performed. The mean-squared multiple-scattering angle effective for planar CR observed in forward direction has been found to be weaker as assumed from scattering in amorphous targets. Scaling laws deduced from the measured CR data are of advantage for the operation of a CR source. The second part of this thesis deals with the possibility of stimulation of CR emission by means of ultrasonic vibrations excited in a piezoelectric single crystal. Since the knowledge of the CR spectra generated on undisturbed quartz crystals is a necessary precondition for some investigation of the influence of US, planar CR has for the first time been measured at medium electron energies for a variety of planes in quartz. As a consequence of the hexagonal structure of this crystal, relative intense CR could be registered even out of planes with indices larger than one. On the base of the non-linear optics method, occupation functions and spectral distributions of planar CR have been calculated for channeling of 20 MeV electrons in the (01 anti 15) plane of a 20 μm thick quartz crystal at resonant influence of ultrasound (US). The resonance frequencies have been deduced from the measurements of CR spectra performed on quartz. First experimental investigations of the influence of US on CR started at ELBE aimed at the study of the effect of non-resonant ultrasonic vibrations excited in a 500 μm thick

  17. Investigation of planar channeling radiation on diamond and quartz crystals at electron energies between 14 and 34 MeV and probing the influence of ultrasonic waves on channeling radiation

    Energy Technology Data Exchange (ETDEWEB)

    Azadegan, B.

    2007-11-15

    Measurements of planar channeling radiation (CR) have been performed at the electron beam of ELBE within an energy range between 14 and 34 MeV and for thicknesses of the diamond crystals between 42.5 and 500 {mu}m. Absolute CR photon yields have for the first time been obtained for the above given ranges of electron energy and crystal thickness. The square-root dependence of the planar CR photon yield on the thickness of diamond crystals has been confirmed. A systematic quantitative investigation of the influence of the crystal thickness on the CR line shape has for the first time been performed. The mean-squared multiple-scattering angle effective for planar CR observed in forward direction has been found to be weaker as assumed from scattering in amorphous targets. Scaling laws deduced from the measured CR data are of advantage for the operation of a CR source. The second part of this thesis deals with the possibility of stimulation of CR emission by means of ultrasonic vibrations excited in a piezoelectric single crystal. Since the knowledge of the CR spectra generated on undisturbed quartz crystals is a necessary precondition for some investigation of the influence of US, planar CR has for the first time been measured at medium electron energies for a variety of planes in quartz. As a consequence of the hexagonal structure of this crystal, relative intense CR could be registered even out of planes with indices larger than one. On the base of the non-linear optics method, occupation functions and spectral distributions of planar CR have been calculated for channeling of 20 MeV electrons in the (01 anti 15) plane of a 20 {mu}m thick quartz crystal at resonant influence of ultrasound (US). The resonance frequencies have been deduced from the measurements of CR spectra performed on quartz. First experimental investigations of the influence of US on CR started at ELBE aimed at the study of the effect of non-resonant ultrasonic vibrations excited in a 500 {mu}m thick

  18. Tables of compound-discount interest rate multipliers for evaluating forestry investments.

    Science.gov (United States)

    Allen L. Lundgren

    1971-01-01

    Tables, prepared by computer, are presented for 10 selected compound-discount interest rate multipliers commonly used in financial analyses of forestry investments. Two set of tables are given for each of the 10 multipliers. The first set gives multipliers for each year from 1 to 40 years; the second set gives multipliers at 5-year intervals from 5 to 160 years....

  19. Study of CP violation in the channel Bd0 → J/ψ(ee)KS0, identification and reconstruction of electrons in the LHCb experiment

    International Nuclear Information System (INIS)

    Terrier, H.

    2005-04-01

    LHCb experiment has been designed in order to do precise measurements of CP violation and rare decays with B mesons. In 2000, the collaboration decided to modify the spectrometer in order to minimize the amount of matter seen by particles and to optimize the trigger. This thesis was done in this context and is divided into 3 parts. The first part is relative to the electron identification and to the recovery of Bremsstrahlung photons emitted by electrons when they pass through matter. Electron identification is mainly based on information provided by calorimeter system but also uses RICH and muon system. A method based on reference histograms had been developed which combine information provided by these detectors. Electron identification efficiency, for electrons in ECAL acceptance is 95% and the pion mis-identification rates 0.8% with a 65% purity of electron sample. Bremsstrahlung recovery allows the selection of J/φ decaying in e + e - pair and of B d 0 → J/φ(ee)K S 0 channel which are described in the second part. The selection of this channel was developed in order to get an acceptable selection efficiency with a good rejection of background. A set of kinematic and topological cuts were designed and total selection efficiency is 0.176%, corresponding to 28000 untagged events reconstructed by year, with a ratio B/S belonging to [0.017;0.069] (at 90% of confidence level) for inclusive bb-bar background. In the third part, B meson flavour tagging is presented. The addition of information provided by the vertex locator allows to reject electron coming from conversion and to improve slightly the performances. The LHCb sensibility to sin(2β) from B 0 → J/ψK S 0 decay is also determined. The statistical error, expected after one year of data collecting, corresponding to an integrated luminosity of 2 fb -1 and bb-bar pair cross section of 0.5 mb, varies from 0.015 to 0.020 according to the values of sin(2β), |λ f | and B/S. (author)

  20. Comparative study of donor-induced quantum dots in Si nano-channels by single-electron transport characterization and Kelvin probe force microscopy

    International Nuclear Information System (INIS)

    Tyszka, K.; Moraru, D.; Samanta, A.; Mizuno, T.; Tabe, M.; Jabłoński, R.

    2015-01-01

    We comparatively study donor-induced quantum dots in Si nanoscale-channel transistors for a wide range of doping concentration by analysis of single-electron tunneling transport and surface potential measured by Kelvin probe force microscopy (KPFM). By correlating KPFM observations of donor-induced potential landscapes with simulations based on Thomas-Fermi approximation, it is demonstrated that single-electron tunneling transport at lowest gate voltages (for smallest coverage of screening electrons) is governed most frequently by only one dominant quantum dot, regardless of doping concentration. Doping concentration, however, primarily affects the internal structure of the quantum dot. At low concentrations, individual donors form most of the quantum dots, i.e., “donor-atom” quantum dots. In contrast, at high concentrations above metal-insulator transition, closely placed donors instead of individual donors form more complex quantum dots, i.e., “donor-cluster” quantum dots. The potential depth of these “donor-cluster” quantum dots is significantly reduced by increasing gate voltage (increasing coverage of screening electrons), leading to the occurrence of multiple competing quantum dots

  1. A multi-channel THz and infrared spectrometer for femtosecond electron bunch diagnostics by single-shot spectroscopy of coherent radiation

    Energy Technology Data Exchange (ETDEWEB)

    Wesch, Stephan; Schmidt, Bernhard; Behrens, Christopher; Delsim-Hashemi, Hossein; Schmueser, Peter

    2011-08-15

    The high peak current required in free-electron lasers (FELs) is realized by longitudinal compression of the electron bunches to sub-picosecond length. In this paper, a frequency-domain diagnostic method is described that is capable of resolving structures in the femtosecond regime. A novel in-vacuum spectrometer has been developed for spectroscopy of coherent radiation in the THz and infrared range. The spectrometer is equipped with five consecutive dispersion gratings and 120 parallel readout channels; it can be operated either in short wavelength mode (5-44 {mu}m) or in long wavelength mode (45-430 {mu}m). Fast parallel readout permits the spectroscopy of coherent radiation from single electron bunches. Test measurements at the soft X-ray free-electron laser FLASH, using coherent transition radiation, demonstrate excellent performance of the spectrometer. The high sensitivity down to a few micrometers allows study of short bunch features caused for example by microbunching e ects in magnetic chicanes. The device is planned for use as an online bunch profile monitor during regular FEL operation. (orig.)

  2. A multi-channel THz and infrared spectrometer for femtosecond electron bunch diagnostics by single-shot spectroscopy of coherent radiation

    International Nuclear Information System (INIS)

    Wesch, Stephan; Schmidt, Bernhard; Behrens, Christopher; Delsim-Hashemi, Hossein; Schmueser, Peter

    2011-08-01

    The high peak current required in free-electron lasers (FELs) is realized by longitudinal compression of the electron bunches to sub-picosecond length. In this paper, a frequency-domain diagnostic method is described that is capable of resolving structures in the femtosecond regime. A novel in-vacuum spectrometer has been developed for spectroscopy of coherent radiation in the THz and infrared range. The spectrometer is equipped with five consecutive dispersion gratings and 120 parallel readout channels; it can be operated either in short wavelength mode (5-44 μm) or in long wavelength mode (45-430 μm). Fast parallel readout permits the spectroscopy of coherent radiation from single electron bunches. Test measurements at the soft X-ray free-electron laser FLASH, using coherent transition radiation, demonstrate excellent performance of the spectrometer. The high sensitivity down to a few micrometers allows study of short bunch features caused for example by microbunching e ects in magnetic chicanes. The device is planned for use as an online bunch profile monitor during regular FEL operation. (orig.)

  3. On centralized power pool auction: a novel multipliers stabilization procedure

    International Nuclear Information System (INIS)

    Jimenez-Redondo, Noemi

    2005-01-01

    This paper addresses the Short-Term Hydro-Thermal Coordination (STHTC) problem. It is a large-scale, combinatorial and nonlinear optimization problem. It is usually solved using a Lagrangian Relaxation (LR) approach. LR procedure is based on the solution of the dual problem of the original one. The dual problem variables are the Lagrange multipliers. These multipliers have an economic meaning: electric energy hourly prices. This paper focuses on an efficient solution of the dual problem of the STHTC problem. A novel multiplier stabilization technique, which significantly improves the quality of the solution, is presented. The provided method could be the optimization tool used by the Independent System Operator of a centralized Power Pool. The solution procedure diminishes the conflict of interest in determining energy prices. A realistic large-scale case study illustrates the behavior of the presented approach. (Author)

  4. New design of an RSFQ parallel multiply-accumulate unit

    International Nuclear Information System (INIS)

    Kataeva, Irina; Engseth, Henrik; Kidiyarova-Shevchenko, Anna

    2006-01-01

    The multiply-accumulate unit (MAC) is a central component of a successive interference canceller, an advanced receiver for W-CDMA base stations. A 4 x 4 two's complement fixed point RSFQ MAC with rounding to 5 bits has been simulated using VHDL, and maximum performance is equal to 24 GMACS (giga-multiply-accumulates per second). The clock distribution network has been re-designed from a linear ripple to a binary tree network in order to eliminate the data dependence of the clock propagation speed and reduce the number of Josephson junctions in clock lines. The 4 x 4 bit MAC has been designed for the HYPRES 4.5 kA cm -2 process and its components have been experimentally tested at low frequency: the 5-bit combiner, using an exhaustive test pattern, had margins on DC bias voltage of ± 18%, and the 4 x 4 parallel multiplier had margins equal to ± 2%

  5. Multiplier Accounting of Indian Mining Industry: The Application

    Science.gov (United States)

    Hussain, Azhar; Karmakar, Netai Chandra

    2017-10-01

    In the previous paper (Hussain and Karmakar in Inst Eng India Ser, 2014. doi: 10.1007/s40033-014-0058-0), the concepts of input-output transaction matrix and multiplier were explained in detail. Input-output multipliers are indicators used for predicting the total impact on an economy due to changes in its industrial demand and output which is calculated using transaction matrix. The aim of this paper is to present an application of the concepts with respect to the mining industry, showing progress in different sectors of mining with time and explaining different outcomes from the results obtained. The analysis shows that a few mineral industries saw a significant growth in their multiplier values over the years.

  6. Dark energy from modified gravity with Lagrange multipliers

    International Nuclear Information System (INIS)

    Capozziello, Salvatore; Matsumoto, Jiro; Nojiri, Shin'ichi; Odintsov, Sergei D.

    2010-01-01

    We study scalar-tensor theory, k-essence and modified gravity with Lagrange multiplier constraint which role is to reduce the number of degrees of freedom. Dark Energy cosmology of different types (ΛCDM, unified inflation with DE, smooth non-phantom/phantom transition epoch) is reconstructed in such models. It is demonstrated that presence of Lagrange multiplier simplifies the reconstruction scenario. It is shown that mathematical equivalence between scalar theory and F(R) gravity is broken due to presence of constraint. The cosmological evolution is defined by the second F 2 (R) function dictated by the constraint. The convenient F(R) gravity sector is relevant for local tests. This opens the possibility to make originally non-realistic theory to be viable by adding the corresponding constraint. A general discussion on the role of Lagrange multipliers to make higher-derivative gravity canonical is developed.

  7. Study on neutron irradiation behavior of beryllium as neutron multiplier

    Energy Technology Data Exchange (ETDEWEB)

    Ishitsuka, Etsuo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

    1998-03-01

    More than 300 tons beryllium is expected to be used as a neutron multiplier in ITER, and study on the neutron irradiation behavior of beryllium as the neutron multiplier with Japan Materials Testing Reactor (JMTR) were performed to get the engineering data for fusion blanket design. This study started as the study on the tritium behavior in beryllium neutron reflector in order to make clear the generation mechanism on tritium of JMTR primary coolant since 1985. These experiences were handed over to beryllium studies for fusion study, and overall studies such as production technology of beryllium pebbles, irradiation behavior evaluation and reprocessing technology have been started since 1990. In this presentation, study on the neutron irradiation behavior of beryllium as the neutron multiplier with JMTR was reviewed from the point of tritium release, thermal properties, mechanical properties and reprocessing technology. (author)

  8. Splay states in globally coupled Josephson arrays: Analytical prediction of Floquet multipliers

    International Nuclear Information System (INIS)

    Strogatz, S.H.; Mirollo, R.E.

    1993-01-01

    In recent numerical experiments on series arrays of overdamped Josephson junctions, Nichols and Wiesenfeld [Phys. Rev. A 45, 8430 (1992)] discovered that the periodic states known as splay states are neutrally stable in all but four directions in phase space. We present a theory that accounts for this enormous degree of neutral stability. The theory also predicts the four non-neutral Floquet multipliers to within 0.1% of their numerically computed values. The analytical approach used here may be appli- cable to other globally coupled systems of oscillators, such as multimode lasers, electronic oscillator circuits, and solid-state laser arrays

  9. Time efficient signed Vedic multiplier using redundant binary representation

    Directory of Open Access Journals (Sweden)

    Ranjan Kumar Barik

    2017-03-01

    Full Text Available This study presents a high-speed signed Vedic multiplier (SVM architecture using redundant binary (RB representation in Urdhva Tiryagbhyam (UT sutra. This is the first ever effort towards extension of Vedic algorithms to the signed numbers. The proposed multiplier architecture solves the carry propagation issue in UT sutra, as carry free addition is possible in RB representation. The proposed design is coded in VHDL and synthesised in Xilinx ISE 14.4 of various FPGA devices. The proposed SVM architecture has better speed performances as compared with various state-of-the-art conventional as well as Vedic architectures.

  10. Radial multipliers on amalgamated free products of II-factors

    DEFF Research Database (Denmark)

    Möller, Sören

    2014-01-01

    Let ℳi be a family of II1-factors, containing a common II1-subfactor 풩, such that [ℳi : 풩] ∈ ℕ0 for all i. Furthermore, let ϕ: ℕ0 → ℂ. We show that if a Hankel matrix related to ϕ is trace-class, then there exists a unique completely bounded map Mϕ on the amalgamated free product of the ℳi...... with amalgamation over 풩, which acts as a radial multiplier. Hereby, we extend a result of Haagerup and the author for radial multipliers on reduced free products of unital C*- and von Neumann algebras....

  11. New stable multiply charged negative atomic ions in linearly polarized superintense laser fields

    International Nuclear Information System (INIS)

    Wei Qi; Kais, Sabre; Moiseyev, Nimrod

    2006-01-01

    Singly charged negative atomic ions exist in the gas phase and are of fundamental importance in atomic and molecular physics. However, theoretical calculations and experimental results clearly exclude the existence of any stable doubly-negatively-charged atomic ion in the gas phase, only one electron can be added to a free atom in the gas phase. In this report, using the high-frequency Floquet theory, we predict that in a linear superintense laser field one can stabilize multiply charged negative atomic ions in the gas phase. We present self-consistent field calculations for the linear superintense laser fields needed to bind extra one and two electrons to form He - , He 2- , and Li 2- , with detachment energies dependent on the laser intensity and maximal values of 1.2, 0.12, and 0.13 eV, respectively. The fields and frequencies needed for binding extra electrons are within experimental reach. This method of stabilization is general and can be used to predict stability of larger multiply charged negative atomic ions

  12. Theory of low-energy electron-molecule collision physics in the coupled-channel method and application to e-CO2 scattering

    International Nuclear Information System (INIS)

    Morrison, M.A.

    1976-08-01

    A theory of electron-molecule scattering based on the fixed-nuclei approximation in a body-fixed reference frame is formulated and applied to e-CO 2 collisions in the energy range from 0.07 to 10.0 eV. The procedure used is a single-center coupled-channel method which incorporates a highly accurate static interaction potential, an approximate local exchange potential, and an induced polarization potential. Coupled equations are solved by a modification of the integral equations algorithm; several partial waves are required in the region of space near the nuclei, and a transformation procedure is developed to handle the consequent numerical problems. The potential energy is converged by separating electronic and nuclear contributions in a Legendre-polynomial expansion and including a large number of the latter. Formulas are derived for total elastic, differential, momentum transfer, and rotational excitation cross sections. The Born and asymptotic decoupling approximations are derived and discussed in the context of comparison with the coupled-channel cross sections. Both are found to be unsatisfactory in the energy range under consideration. An extensive discussion of the technical aspects of calculations for electron collisions with highly nonspherical targets is presented, including detailed convergence studies and a discussion of various numerical difficulties. The application to e-CO 2 scattering produces converged results in good agreement with observed cross sections. Various aspects of the physics of this collision are discussed, including the 3.8 eV shape resonance, which is found to possess both p and f character, and the anomalously large low-energy momentum transfer cross sections, which are found to be due to Σ/sub g/ symmetry. Comparison with static and static-exchange approximations are made

  13. Computer aided design (CAD) for electronics improvement of the nuclear channels of TRIGA Mark III reactor of the ININ

    International Nuclear Information System (INIS)

    Gonzalez M, J.L.; Rivero G, T.; Aguilar H, F.

    2007-01-01

    The 4 neutron measurement channels of the digital control console (CCD) of the TRIGA Mark III reactor (RTMIII) of the ININ, its were designed and built with the corresponding Quality Guarantee program, being achieved the one licensing to replace the old console. With the time they were carried out some changes to improve and to not solve some problems detected in the tests, verification and validation, requiring to modify the circuits originally designed. In this work the corrective actions carried out to eliminate the Non Conformity generated by these problems, being mentioned the advantages of using modern tools, as the software applied to the Attended Engineering by Computer, and those obtained results are presented. (Author)

  14. Electron measurements and search for Higgs bosons in multi-lepton channels with the CMS experiment at LHC

    International Nuclear Information System (INIS)

    Broutin, C.

    2011-07-01

    This thesis presents three years of work with the CMS experiment, in the context of the first LHC collisions. Electron objects were studied in particular, as major tools for multi-lepton analyses, in particular the H → ZZ(*) → 4l analysis. During the first months of collisions, we took part in the validation of data registered by the electromagnetic calorimeter. We also measured the efficiency of the level-1 electron and photon trigger during the whole 2010 year. The plateau efficiency is of 99.6% (resp. 98.5 %) on electrons in the barrel part (resp. in the end cap part) of the calorimeter. In order to optimize the discovery potential, we built a new electron charge measurement algorithm. In CMS, this measurement is affected by the large amount of material present in the inner tracker. The performance of this algorithm was measured on 2010 data, for electrons from Z boson decay passing a standard selection. The probability of charge mis-identification is of 1.06% (0.19% with a specific selection), in agreement with the simulation. The physics analysis that was built during this PhD searches doubly charged Higgs bosons decaying into lepton pairs. For the amount of data registered in 2010, one background event is expected to pass the selection, while the amount of signal events depends on the mass hypothesis and on the model. One event was found on data, in agreement with the background expectation, hence the signal was excluded on larger mass ranges than previous experiments: a mass limit was set between 122 GeV/c 2 and 176 GeV/c 2 , depending on the model. (author)

  15. ANALYSIS OF THE INVESTMENT ARBITRAGE STRATEGY USING FINANCIAL MULTIPLIERS

    Directory of Open Access Journals (Sweden)

    Dmitry S. Pashkov

    2013-01-01

    Full Text Available This article describes an algorithm for stock pairs trading using financial multipliers of underlying companies. This algorithm has been tested on historical data and compared with classical Bollinger bands strategy. The results of tests were presented for two financial sectors of US stock market.

  16. Garbage-free reversible constant multipliers for arbitrary integers

    DEFF Research Database (Denmark)

    Mogensen, Torben Ægidius

    2013-01-01

    We present a method for constructing reversible circuitry for multiplying integers by arbitrary integer constants. The method is based on Mealy machines and gives circuits whose size are (in the worst case) linear in the size of the constant. This makes the method unsuitable for large constants...

  17. Smooth bifurcation for variational inequalities based on Lagrange multipliers

    Czech Academy of Sciences Publication Activity Database

    Eisner, Jan; Kučera, Milan; Recke, L.

    2006-01-01

    Roč. 19, č. 9 (2006), s. 981-1000 ISSN 0893-4983 R&D Projects: GA AV ČR(CZ) IAA100190506 Institutional research plan: CEZ:AV0Z10190503 Keywords : abstract variational inequality * bifurcation * Lagrange multipliers Subject RIV: BA - General Mathematics

  18. Detection of differential item functioning using Lagrange multiplier tests

    NARCIS (Netherlands)

    Glas, Cornelis A.W.

    1998-01-01

    Abstract: In the present paper it is shown that differential item functioning can be evaluated using the Lagrange multiplier test or Rao’s efficient score test. The test is presented in the framework of a number of IRT models such as the Rasch model, the OPLM, the 2-parameter logistic model, the

  19. Detection of differential item functioning using Lagrange multiplier tests

    NARCIS (Netherlands)

    Glas, Cornelis A.W.

    1996-01-01

    In this paper it is shown that differential item functioning can be evaluated using the Lagrange multiplier test or C. R. Rao's efficient score test. The test is presented in the framework of a number of item response theory (IRT) models such as the Rasch model, the one-parameter logistic model, the

  20. Lagrange-multiplier tests for weak exogeneity: a synthesis.

    NARCIS (Netherlands)

    Boswijk, H.P.; Urbain, J.P.

    1997-01-01

    This paper unifies two seemingly separate approaches to test weak exogeneity in dynamic regression models with Lagrange-multiplier statistics. The first class of tests focuses on the orthogonality between innovations and conditioning variables, and thus is related to the Durbin-Wu-Hausman

  1. Fiscal multipliers over the growth cycle : evidence from Malaysia

    OpenAIRE

    Rafiq, Sohrab; Zeufack, Albert

    2012-01-01

    This paper explores the stabilisation properties of fiscal policy in Malaysia using a model incorporating nonlinearities into the dynamic relationship between fiscal policy and real economic activity over the growth cycle. The paper also investigates how output multipliers for government purchases may alter for different components of government spending. The authors find that fiscal polic...

  2. A database analysis of information on multiply charged ions

    International Nuclear Information System (INIS)

    Delcroix, J.L.

    1989-01-01

    A statistical analysis of data related to multiply charged ions, is performed in GAPHYOR data base: over-all statistics by ionization degree from q=1 to q=99, 'historical' development from 1975 to 1987, distribution (for q≥ 5) over physical processes (energy levels, charge exchange,...) and chemical elements

  3. Multiple images of our galaxy in closed, multiply connected cosmologies

    International Nuclear Information System (INIS)

    Fagundes, H.V.

    1985-01-01

    Friedmanian cosmology with multiply connected spatial sections allows multiple images of cosmic sources, in particular of the galaxy itself. This is illustrated with a specific example of a closed hyperbolic model and a brief mention of a spherical model. Such images may eventually become observable (or recognized as such), thus providing a new test of relativistic cosmology. (Author) [pt

  4. A CMOS four-quadrant analog current multiplier

    NARCIS (Netherlands)

    Wiegerink, Remco J.

    1991-01-01

    A CMOS four-quadrant analog current multiplier is described. The circuit is based on the square-law characteristic of an MOS transistor and is insensitive to temperature and process variations. The circuit is insensitive to the body effect so it is not necessary to place transistors in individual

  5. The evolution of unconditional strategies via the 'multiplier effect'.

    Science.gov (United States)

    McNamara, John M; Dall, Sasha R X

    2011-03-01

    Ostensibly, it makes sense in a changeable world to condition behaviour and development on information when it is available. Nevertheless, unconditional behavioural and life history strategies are widespread. Here, we show how intergenerational effects can limit the evolutionary value of responding to reliable environmental cues, and thus favour the evolutionary persistence of otherwise paradoxical unconditional strategies. While cue-ignoring genotypes do poorly in the wrong environments, in the right environment they will leave many copies of themselves, which will themselves leave many copies, and so on, leading genotypes to accumulate in habitats in which they do well. We call this 'The Multiplier Effect'. We explore the consequences of the multiplier effect by focussing on the ecologically important phenomenon of natal philopatry. We model the environment as a large number of temporally varying breeding sites connected by natal dispersal between sites. Our aim is to identify which aspects of an environment promote the multiplier effect. We show, if sites remain connected through some background level of 'accidental' dispersal, unconditional natal philopatry can evolve even when there is density dependence (with its accompanying kin competition effects), and cues that are only mildly erroneous. Thus, the multiplier effect may underpin the evolution and maintenance of unconditional strategies such as natal philopatry in many biological systems. © 2011 Blackwell Publishing Ltd/CNRS.

  6. A cascaded three-phase symmetrical multistage voltage multiplier

    International Nuclear Information System (INIS)

    Iqbal, Shahid; Singh, G K; Besar, R; Muhammad, G

    2006-01-01

    A cascaded three-phase symmetrical multistage Cockcroft-Walton voltage multiplier (CW-VM) is proposed in this report. It consists of three single-phase symmetrical voltage multipliers, which are connected in series at their smoothing columns like string of batteries and are driven by three-phase ac power source. The smoothing column of each voltage multiplier is charged twice every cycle independently by respective oscillating columns and discharged in series through load. The charging discharging process completes six times a cycle and therefore the output voltage ripple's frequency is of sixth order of the drive signal frequency. Thus the proposed approach eliminates the first five harmonic components of load generated voltage ripples and sixth harmonic is the major ripple component. The proposed cascaded three-phase symmetrical voltage multiplier has less than half the voltage ripple, and three times larger output voltage and output power than the conventional single-phase symmetrical CW-VM. Experimental and simulation results of the laboratory prototype are given to show the feasibility of proposed cascaded three-phase symmetrical CW-VM

  7. Robust formation control of marine surface craft using Lagrange multipliers

    DEFF Research Database (Denmark)

    Ihle, Ivar-Andre F.; Jouffroy, Jerome; Fossen, Thor I.

    2006-01-01

    This paper presents a formation modelling scheme based on a set of inter-body constraint functions and Lagrangian multipliers. Formation control for a °eet of marine craft is achieved by stabilizing the auxiliary constraints such that the desired formation con¯guration appears. In the proposed fr...

  8. Familiar Sports and Activities Adapted for Multiply Impaired Persons.

    Science.gov (United States)

    Schilling, Mary Lou, Ed.

    1984-01-01

    Means of adapting some familiar and popular physical activities for multiply impaired persons are described. Games reviewed are dice baseball, one base baseball, in-house bowling, wheelchair bowling, ramp bowling, swing-ball bowling, table tennis, shuffleboard, beanbag bingo and tic-tac-toe, balloon basketball, circle football, and wheelchair…

  9. Very high channel conductivity in low-defect AlN/GaN high electron mobility transistor structures

    International Nuclear Information System (INIS)

    Dabiran, A. M.; Wowchak, A. M.; Osinsky, A.; Xie, J.; Hertog, B.; Cui, B.; Chow, P. P.; Look, D. C.

    2008-01-01

    Low defect AlN/GaN high electron mobility transistor (HEMT) structures, with very high values of electron mobility (>1800 cm 2 /V s) and sheet charge density (>3x10 13 cm -2 ), were grown by rf plasma-assisted molecular beam epitaxy (MBE) on sapphire and SiC, resulting in sheet resistivity values down to ∼100 Ω/□ at room temperature. Fabricated 1.2 μm gate devices showed excellent current-voltage characteristics, including a zero gate saturation current density of ∼1.3 A/mm and a peak transconductance of ∼260 mS/mm. Here, an all MBE growth of optimized AlN/GaN HEMT structures plus the results of thin-film characterizations and device measurements are presented

  10. Electron spin echo envelope modulation (ESEEM) reveals water and phosphate interactions with the KcsA potassium channel

    OpenAIRE

    Cieslak, John A.; Focia, Pamela J.; Gross, Adrian

    2010-01-01

    Electron spin-echo envelope modulation (ESEEM) spectroscopy is a well-established technique for the study of naturally occurring paramagnetic metal centers. The technique has been used to study copper complexes, hemes, enzyme mechanisms, micellar water content, and water permeation profiles in membranes, among other applications. In the present study, we combine ESEEM spectroscopy with site-directed spin labeling (SDSL) and X-ray crystallography in order to evaluate the technique's potential ...

  11. High electron mobility recovery in AlGaN/GaN 2DEG channels regrown on etched surfaces

    International Nuclear Information System (INIS)

    Chan, Silvia H; DenBaars, Steven P; Keller, Stacia; Tahhan, Maher; Li, Haoran; Romanczyk, Brian; Mishra, Umesh K

    2016-01-01

    This paper reports high two-dimensional electron gas mobility attained from the regrowth of the AlGaN gating layer on ex situ GaN surfaces. To repair etch-damaged GaN surfaces, various pretreatments were conducted via metalorganic chemical vapor deposition, followed by a regrown AlGaN/GaN mobility test structure to evaluate the extent of recovery. The developed treatment process that was shown to significantly improve the electron mobility consisted of a N 2  + NH 3 pre-anneal plus an insertion of a 4 nm or thicker GaN interlayer prior to deposition of the AlGaN gating layer. Using the optimized process, a high electron mobility transistor (HEMT) device was fabricated which exhibited a high mobility of 1450 cm 2 V −1 s −1 (R sh  = 574 ohm/sq) and low dispersion characteristics. The additional inclusion of an in situ Al 2 O 3 dielectric into the regrowth process for MOS-HEMTs still preserved the transport properties near etch-impacted areas. (paper)

  12. Performance of 8- and 12-dynode stage multianode photo-multipliers

    Energy Technology Data Exchange (ETDEWEB)

    Bibby, J.H. [University of Oxford, Oxford (United Kingdom); Buckley, A. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Chamonal, R.J.U. [University of Edinburgh, Edinburgh (United Kingdom)]. E-mail: chamonal@ph.ed.ac.uk; Easo, S. [CCLRC, Rutherford Aplleton Laboratory, Chilton, Didcot, Oxfordshire (United Kingdom); Eisenhardt, S. [University of Edinburgh, Edinburgh (United Kingdom); Gibson, V. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Harnew, N. [University of Oxford, Oxford (United Kingdom); Muheim, F. [University of Edinburgh, Edinburgh (United Kingdom); Howard, A. [Imperial College, London (United Kingdom); Lawrence, J. [University of Edinburgh, Edinburgh (United Kingdom); Pickford, A. [University of Glasgow, Glasgow (United Kingdom); Plackett, R. [Imperial College, London (United Kingdom); Price, D.R. [Imperial College, London (United Kingdom); Rademacker, J. [University of Oxford, Oxford (United Kingdom); Smale, N. [University of Oxford, Oxford (United Kingdom); Soler, F.J.P. [University of Glasgow, Glasgow (United Kingdom); CCLRC, Rutherford Aplleton Laboratory, Chilton, Didcot, Oxfordshire (United Kingdom); Somerville, L. [University of Oxford, Oxford (United Kingdom); Storey, J. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Websdale, D. [Imperial College, London (United Kingdom); Wotton, S. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom)

    2006-11-01

    We report on studies of 64-channel Multianode Photo-Multiplier Tubes (MaPMTs) as photo-detectors for Ring Imaging CHerenkov (RICH) counters. The newly available 8-dynode stage MaPMT was tested in particle beams at CERN. The MaPMT signals were read out directly with the Beetle1.2 chip which was designed for the LHCb environment and operates at 40MHz. The photon yield and signal losses were determined for a cluster of 3x3 close-packed MaPMTs. The performance of the 8-dynode stage MaPMT was compared to that of the 12-dynode stage MaPMT which has a larger intrinsic gain.

  13. An electron back-scattered diffraction study on the microstructure evolution of AZ31 Mg alloy during equal channel angular extrusion

    International Nuclear Information System (INIS)

    Jin Li; Lin Dongliang; Mao Dali; Zeng Xiaoqin; Ding Wenjiang

    2006-01-01

    Microstructure evolution of AZ31 Mg alloy during equal channel angular extrusion (ECAE) was investigated by electron back-scattered diffraction (EBSD). The grains of AZ31 Mg alloy were refined significantly after ECAE 1-8 passes at 498 K and the distributions of grain size tended to be more uniform with pass number increasing. Frequency of sub-boundaries and low angle grain boundaries (LAGBs) increased at initial stage of deformation, and sub-boundaries and LAGBs evolved into high angle grain boundaries (HAGBs) with further deformation, which resulted in the high frequency of HAGBs in the alloy after ECAE 8 passes. Preferred misorientation angle with frequency peak near 30 deg. and 90 deg. were observed. The frequency peaks were weak after ECAE 1 pass but became stronger with the increase of pass numbers. Micro-textures were formed in AZ31 microstructure during ECAE and were stronger with the pass number increasing

  14. Intergrown new zeolite beta polymorphs with interconnected 12-ring channels solved by combining electron crystallography and single-crystal X-ray diffraction

    KAUST Repository

    Yu, Zhengbao

    2012-10-09

    Two new polymorphs of zeolite beta, denoted as SU-78A and SU-78B, were synthesized by employing dicyclohexylammonium hydroxides as organic structure-directing agents. The structure was solved by combining transmission electron microscopy and single-crystal X-ray diffraction. SU-78 is an intergrowth of SU-78A and SU-78B and contains interconnected 12-ring channels in three directions. The two polymorphs are built from the same building layer, similar to that for the zeolite beta family. The layer stacking in SU-78, however, is different from those in zeolite beta polymorph A, B, and C, showing new zeolite framework topologies. SU-78 is thermally stable up to 600 °C. © 2012 American Chemical Society.

  15. Investigation of enhancement-mode AlGaN/GaN nanowire channel high-electron-mobility transistor with oxygen-containing plasma treatment

    Science.gov (United States)

    He, Yunlong; Wang, Chong; Mi, Minhan; Zhang, Meng; Zhu, Qing; Zhang, Peng; Wu, Ji; Zhang, Hengshuang; Zheng, Xuefeng; Yang, Ling; Duan, Xiaoling; Ma, Xiaohua; Hao, Yue

    2017-05-01

    A novel enhancement-mode (E-mode) AlGaN/GaN high-electron-mobility transistor (HEMT) has been fabricated, by combining nanowire channel (NC) structure fabrication and N2O (or O2) plasma treatment. A comparison of two NC-HEMTs with different plasma treatments has been made. The NC-HEMT with N2O plasma treatment shows an output current of 610 mA/mm and a peak transconductance of 450 mS/mm. The DIBL of the NC-HEMT with N2O plasma treatment is as low as 2 mV/V, and an SS of 70 mV/decade is achieved. The device exhibits an intrinsic current gain cutoff frequency f T of 19 GHz and a maximum oscillation frequency f max of 58 GHz.

  16. Electron collisions with phenol: Total, integral, differential, and momentum transfer cross sections and the role of multichannel coupling effects on the elastic channel

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Romarly F. da [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, 13083-859 Campinas, São Paulo (Brazil); Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-580 Santo André, São Paulo (Brazil); Oliveira, Eliane M. de; Lima, Marco A. P. [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, 13083-859 Campinas, São Paulo (Brazil); Bettega, Márcio H. F. [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Varella, Márcio T. do N. [Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo (Brazil); Jones, Darryl B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide SA 5001 (Australia); Brunger, Michael J. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Blanco, Francisco [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, Ciudad Universitaria, 2840 Madrid (Spain); Colmenares, Rafael [Hospital Ramón y Cajal, 28034 Madrid (Spain); and others

    2015-03-14

    We report theoretical and experimental total cross sections for electron scattering by phenol (C{sub 6}H{sub 5}OH). The experimental data were obtained with an apparatus based in Madrid and the calculated cross sections with two different methodologies, the independent atom method with screening corrected additivity rule (IAM-SCAR), and the Schwinger multichannel method with pseudopotentials (SMCPP). The SMCPP method in the N{sub open}-channel coupling scheme, at the static-exchange-plus-polarization approximation, is employed to calculate the scattering amplitudes at impact energies ranging from 5.0 eV to 50 eV. We discuss the multichannel coupling effects in the calculated cross sections, in particular how the number of excited states included in the open-channel space impacts upon the convergence of the elastic cross sections at higher collision energies. The IAM-SCAR approach was also used to obtain the elastic differential cross sections (DCSs) and for correcting the experimental total cross sections for the so-called forward angle scattering effect. We found a very good agreement between our SMCPP theoretical differential, integral, and momentum transfer cross sections and experimental data for benzene (a molecule differing from phenol by replacing a hydrogen atom in benzene with a hydroxyl group). Although some discrepancies were found for lower energies, the agreement between the SMCPP data and the DCSs obtained with the IAM-SCAR method improves, as expected, as the impact energy increases. We also have a good agreement among the present SMCPP calculated total cross section (which includes elastic, 32 inelastic electronic excitation processes and ionization contributions, the latter estimated with the binary-encounter-Bethe model), the IAM-SCAR total cross section, and the experimental data when the latter is corrected for the forward angle scattering effect [Fuss et al., Phys. Rev. A 88, 042702 (2013)].

  17. The resistive plate WELL detector as a single stage thick gaseous multiplier detector

    Energy Technology Data Exchange (ETDEWEB)

    Bressler, Shikma; Breskin, Amos; Moleri, Luca; Kumar, Ashwini; Pitt, Michael [Department of Particle Physics and Astrophysics, Weizmann Institute of Science (WIS) (Israel); Kudella, Simon [Institut fuer Experimentelle Kernphysik (IEKP), KIT (Germany)

    2015-07-01

    Gaseous Electron Multiplier (GEM) detector use high electric fields inside the h ole of a foil to achieve a high charge multiplication. As a thicker version of G EMs based on printed circuit board (PCB) structures, Thick Gaseous Electron Multiplier (THGEM) detectors combine the high gain of a GEM foil with the robustness, stability and low production costs of a PCB and allow a large quantity of applications that require the coverage of a large area at low cost and moderate spatial resolution. One application the Weizmann Institute of Science (WIS) develops as a member of the RD51 framework is the Resistive Plate WELL (RPWELL) detector. This single stage detector allows a very stable, discharge free operation at high gain (10{sup 5}). The single stage operation allows a low total height and make s the RPWELL a candidate for the Digital Hadronic Calorimeter (DHCAL) of the International Large Detector (ILD) at the International Linear Collider (ILC). The talk gives an insight into the way the RPWELL works and shows results from the last test beam.

  18. Validation of tracker alignment using electrons, and search for long-lived particles in the electron-muon channel, in the CMS experiment at LHC

    International Nuclear Information System (INIS)

    Goetzmann, Christophe

    2014-01-01

    The first part of my work concerns the development of an algorithm using CMS data to automatically detect the presence of particular deformations than can occur in the CMS tracker. The method takes advantage of the bias that such deformations induce in the measurement of electron impulsion. The reliability of the method has been proved using Monte-Carlo simulation. The algorithm was then used to certify that none of the considered deformations affected the data recorded in 2012. The second part of my work consists of a statistical analysis of the data recorded by CMS, in order to look for evidence of the presence of exotic long-lived particles. The latter could manifest themselves through their decay to an electron and a muon. Such an observation would provide a strong clue of the existence of new physics. In the absence of any observation statistically significant, a Bayesian method is used to interpret this result in term of constraints on a supersymmetric model (MSSM). (author)

  19. Performances of the electromagnetic calorimeter and search for new gauge bosons in the di-electron channel at the LHC

    International Nuclear Information System (INIS)

    Laisne, E.

    2012-10-01

    The Standard Model of particle physics has known a tremendous rise during the twentieth century. Built up, from the early thirties to the seventies, this theory describing elementary particles and their interactions (electromagnetic, weak, strong) has now been intensively tested by LEP and Tevatron colliders. Besides its success, some problems remain and have lead to new theories attempting to go beyond the standard model. Many of them are predicting the existence of a new gauge boson Z', which is supposed to be observed at the TeV scale. Data recorded by the LHC since autumn 2008 are a new opportunity to check the consistency of the Standard Model and to search for new physics evidence. The work that has been done by the ATLAS collaboration during the last four years has focused on understanding detector's behaviour and analysing the very first collected collisions. This thesis is reflecting these two aspects. Therefore, the first part of this thesis describes the characterisation of a pathology of ATLAS liquid argon calorimeter electronics and of coherent noise bursts that have both been observed since the beginning of ATLAS operation. The policy deployed to preserve data quality is also detailed. The second part is focusing on the search for new Z' gauge boson. In case this particle was to exist, its decay into an electron and a positron would lead to a new massive resonance in the dielectron invariant mass spectrum. Therefore electron reconstruction and identification performances are closely looked at, especially at high transverse momentum. Analysis made on the 4.9 fb -1 of collected data is reported. As no significant excess with respect to Standard Model predictions is observed, the dielectron invariant mass spectrum is interpreted to derive mass limits concerning the existence of new Z' gauge bosons appearing in grand unification theories (E6) and effective sequential standard model (SSM). These limits and those derived by the CMS collaboration are the

  20. Control of short-channel effects in InAlN/GaN high-electron mobility transistors using graded AlGaN buffer

    Science.gov (United States)

    Han, Tiecheng; Zhao, Hongdong; Peng, Xiaocan; Li, Yuhai

    2018-04-01

    A graded AlGaN buffer is designed to realize the p-type buffer by inducing polarization-doping holes. Based on the two-dimensional device simulator, the effect of the graded AlGaN buffer on the direct-current (DC) and radio-frequency (RF) performance of short-gate InAlN/GaN high-electron mobility transistors (HEMTs) are investigated, theoretically. Compared to standard HEMT, an enhancement of electron confinement and a good control of short-channel effect (SCEs) are demonstrated in the graded AlGaN buffer HEMT. Accordingly, the pinched-off behavior and the ability of gate modulation are significantly improved. And, no serious SCEs are observed in the graded AlGaN buffer HEMT with an aspect ratio (LG/tch) of about 6.7, much lower than that of the standard HEMT (LG/tch = 13). In addition, for a 70-nm gate length, a peak current gain cutoff frequency (fT) of 171 GHz and power gain cutoff frequency (fmax) of 191 GHz are obtained in the grade buffer HEMT, which are higher than those of the standard one with the same gate length.

  1. Design studies for an advanced ECR ion source for multiply charged ion beam generation

    International Nuclear Information System (INIS)

    Alton, G.D.

    1994-01-01

    An innovative technique: for increasing ion source intensity is described which, in principle, could lead to significant advances in ECR ion source technology for multiply charged ion beam formation. The advanced concept design uses a minimum-B magnetic mirror geometry which consists of a multi-cusp, magnetic field, to assist in confining the plasma radially, a flat central field for tuning to the ECR resonant condition, and specially tailored min-or fields in the end zones to confine the plasma in the axial direction. The magnetic field is designed to achieve an axially symmetric plasma ''volume'' with constant mod-B, which extends over the length of the central field region. This design, which strongly contrasts w h the ECR ''surfaces'' characteristic of conventional ECR ion sources, results in dramatic increases in the absorption of RF power, thereby increasing the electron temperature and ''hot'' electron population within the ionization volume of the source

  2. Characterization of photo-multiplier tube as ex-vessel radiation detector in tokamak

    Science.gov (United States)

    Jo, Jungmin; Cheon, MunSeong; Kim, Junghee; An, YoungHwa; Park, Seungil; Chung, Kyoung-Jae; Hwang, Y. S.

    2017-09-01

    Feasibility of using conventional photo-multiplier tubes (PMTs) without a scintillator as an ex-vessel radiation detector in a tokamak environment is studied. Basic irradiation tests using standard gamma ray sources and a d-d neutron generator showed that the PMT is responding both to gamma photons and neutrons, possibly due to the direct generation of secondary electrons inside the PMT by the impingement of high energy photons. Because of the selective sensitivity of the PMT to hard x-ray and neutrons in ohmic and neutral beam injected plasmas, respectively, it is shown that the PMT with certain configuration can be utilized either to monitor the fluctuation in the fusion neutron generation rate or to study the behavior of runaway electrons in tokamaks.

  3. Californium Multiplier. Part I. Design for neutron radiography

    International Nuclear Information System (INIS)

    Crosbie, K.L.; Preskitt, C.A.; John, J.; Hastings, J.D.

    1982-01-01

    The Californium Multiplier (CFX) is a subcritical assembly of enriched uranium surrounding a californium-252 neutron source. The function of the CFX is to multiply the neutrons emitted by the source to a number sufficient for neutron radiography. The CFX is designed to provide a collimated beam of thermal neutrons from which the gamma radiation is filtered, and the scattered neutrons are reduced to make it suitable for high resolution radiography. The entire system has inherent safety features, which provide for system and personnel safety, and it operates at moderate cost. In Part I, the CFX and the theory of its operation are described in detail. Part II covers the performance of the Mound Facility CFX

  4. Generation of fast multiply charged ions in conical targets

    International Nuclear Information System (INIS)

    Demchenko, V.V.; Chukbar, K.V.

    1990-01-01

    So-called conical targets, when the thermonuclear fuel is compressed and heated in a conical cavity in a heavy material (lead, gold, etc.) with the help of a spherical segment that is accelerated by a laser pulse or a beam of charged particles, are often employed in experimental studies of inertial-confinement fusion. In spite of the obvious advantages of such a scheme, one of which is a significant reduction of the required energy input compared with the complete spherical target, it also introduces additional effects into the process of cumulation of energy. In this paper the authors call attention to an effect observed in numerical calculations: the hydrodynamic heating of a small group of multiply charged heavy ions of the walls of the conical cavity up to high energies (T i approx-gt 100 keV). This effect ultimately occurs as a result of the high radiation losses of a multiply charged plasma

  5. Electron capture to the continuum from atomic hydrogen

    International Nuclear Information System (INIS)

    Glass, G.A.; Engar, P.; Berry, S.D.; Breinig, M.; Deserio, R.; Elston, S.B.; Sellin, I.A.

    1984-01-01

    The first known measurement of the differential cross section for electron capture to the continuum(ECC) from atomic hydrogen is presented. A 12 MeV beam of C 6+ ions traversed a static target of atomic hydrogen produced by an electron impact heated dissociation oven. The resulting ECC spectrum was obtained with a channel electron multiplier detector mounted at the exit of a 160 0 spherical sector electrostatic spectrometer with an angular acceptance of 2 0 . The ECC spectrum clearly shows the asymmetry generally associated with ECC spectra from gaseous targets. The ratio of the singly differential cross section of H to that of H 2 was found to be 0.80. 16 references, 3 figures

  6. Inverse mass matrix via the method of localized lagrange multipliers

    Czech Academy of Sciences Publication Activity Database

    González, José A.; Kolman, Radek; Cho, S.S.; Felippa, C.A.; Park, K.C.

    2018-01-01

    Roč. 113, č. 2 (2018), s. 277-295 ISSN 0029-5981 R&D Projects: GA MŠk(CZ) EF15_003/0000493; GA ČR GA17-22615S Institutional support: RVO:61388998 Keywords : explicit time integration * inverse mass matrix * localized Lagrange multipliers * partitioned analysis Subject RIV: BI - Acoustics OBOR OECD: Applied mechanics Impact factor: 2.162, year: 2016 https://onlinelibrary.wiley.com/doi/10.1002/nme.5613

  7. On Lagrange Multipliers in Work with Quality and Reliability Assurance

    DEFF Research Database (Denmark)

    Vidal, Rene Victor Valqui; Becker, P.

    1986-01-01

    In optimizing some property of a system, reliability say, a designer usually has to accept certain constraints regarding cost, completion time, volume, weight, etc. The solution of optimization problems with boundary constraints can be helped substantially by the use of Lagrange multipliers...... in the areas of sales promotion and teaching. These maps illuminate the logic structure of solution sequences. One such map is shown, illustrating the application of LMT in one of the examples....

  8. Characterization of a prototype matrix of Silicon PhotoMultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Dinu, N. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France)], E-mail: dinu@lal.in2p3.fr; Barrillon, P.; Bazin, C. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Belcari, N.; Bisogni, M.G. [Universita di Pisa, Dipartimento di Fisica ' E. Fermi' , 56127 Pisa (Italy); INFN, Sezione di Pisa, 56127 Pisa (Italy); Bondil-Blin, S. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Boscardin, M. [Fondazione Bruno Kessler (FBK-irst), 38050 Trento (Italy); Chaumat, V. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Collazuol, G. [Scuola Normale Superiore (SNS), 56127 Pisa (Italy); INFN, Sezione di Pisa, 56127 Pisa (Italy); De La Taille, C. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Del Guerra, A. [Universita di Pisa, Dipartimento di Fisica ' E. Fermi' , 56127 Pisa (Italy); INFN, Sezione di Pisa, 56127 Pisa (Italy); Llosa, G. [Universita di Pisa, Dipartimento di Fisica ' E. Fermi' , 56127 Pisa (Italy); Marcatili, S. [Universita di Pisa, Dipartimento di Fisica ' E. Fermi' , 56127 Pisa (Italy); INFN, Sezione di Pisa, 56127 Pisa (Italy); Melchiorri, M.; Piemonte, C. [Fondazione Bruno Kessler (FBK-irst), 38050 Trento (Italy); Puill, V. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Tarolli, A. [Fondazione Bruno Kessler (FBK-irst), 38050 Trento (Italy); Vagnucci, J.F. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Zorzi, N. [Fondazione Bruno Kessler (FBK-irst), 38050 Trento (Italy)

    2009-10-21

    This work reports on the electrical as well as the optical characterizations of a prototype matrix of Silicon PhotoMultipliers (SiPM). The electrical test consists of the measurement of the static (breakdown voltage, quenching resistance, post-breakdown dark current) as well as the dynamic characteristics (gain, dark count rate). The optical test consists of the estimation of the photon detection efficiency as a function of wavelength as well as operation voltage.

  9. Characterization of a prototype matrix of Silicon PhotoMultipliers

    International Nuclear Information System (INIS)

    Dinu, N.; Barrillon, P.; Bazin, C.; Belcari, N.; Bisogni, M.G.; Bondil-Blin, S.; Boscardin, M.; Chaumat, V.; Collazuol, G.; De La Taille, C.; Del Guerra, A.; Llosa, G.; Marcatili, S.; Melchiorri, M.; Piemonte, C.; Puill, V.; Tarolli, A.; Vagnucci, J.F.; Zorzi, N.

    2009-01-01

    This work reports on the electrical as well as the optical characterizations of a prototype matrix of Silicon PhotoMultipliers (SiPM). The electrical test consists of the measurement of the static (breakdown voltage, quenching resistance, post-breakdown dark current) as well as the dynamic characteristics (gain, dark count rate). The optical test consists of the estimation of the photon detection efficiency as a function of wavelength as well as operation voltage.

  10. Radial multipliers on reduced free products of operator algebras

    DEFF Research Database (Denmark)

    Haagerup, Uffe; Møller, Søren

    2012-01-01

    Let AiAi be a family of unital C¿C¿-algebras, respectively, of von Neumann algebras and ¿:N0¿C¿:N0¿C. We show that if a Hankel matrix related to ¿ is trace-class, then there exists a unique completely bounded map M¿M¿ on the reduced free product of the AiAi, which acts as a radial multiplier...

  11. Study of the electric field inside microchannel plate multipliers

    International Nuclear Information System (INIS)

    Gatti, E.; Oba, K.; Rehak, P.

    1982-01-01

    Electric field inside high gain microchannel plate multipliers was studied. The calculations were based directly on the solution of the Maxwell equations applied to the microchannel plate (MCP) rather than on the conventional lumped RC model. The results are important to explain the performance of MCP's, (1) under a pulsed bias tension and, (2) at high rate conditions. The results were tested experimentally and a new method of MCP operation free from the positive ion feedback was demonstrated

  12. Neutralization of H-- in energetic collisions with multiply charged ions

    International Nuclear Information System (INIS)

    Melchert, F.; Benner, M.; Kruedener, S.; Schulze, R.; Meuser, S.; Huber, K.; Salzborn, E.; Uskov, D.B.; Presnyakov, L.P.

    1995-01-01

    Employing the crossed-beam technique, we have measured absolute cross sections for neutralization of H -- ions in collisions with multiply charged ions Ne q+ (q≤4) and Ar q+ , Xe q+ (q≤8) at center-of-mass energies ranging from 20 to 200 keV. . . It is found that th cross sections are independent of the target ion species. The data are in excellent agreement with quantum calculations. A universal scaling law for the neutralization cross section is given

  13. Estimates for Unimodular Multipliers on Modulation Hardy Spaces

    Directory of Open Access Journals (Sweden)

    Jiecheng Chen

    2013-01-01

    Full Text Available It is known that the unimodular Fourier multipliers eit|Δ|α/2, α>0, are bounded on all modulation spaces Mp,qs for 1≤p,q≤∞. We extend such boundedness to the case of all 00 and obtain the local well-posedness for the Cauchy problem of some nonlinear partial differential equations with fundamental semigroup eit|Δ|α/2.

  14. Measurement of the production cross section for W + γ in the electron channel in √s = 1.8 TeV bar pp collisions

    International Nuclear Information System (INIS)

    Benjamin, D.P.

    1993-11-01

    The production cross section times decay branching ratio for W +γ in the electron decay channel in √s = 1.8 TeV bar p-p collisions has been measured using W → eγ data sample obtained from the CDF 1988--1989 Tevatron collider run. For photons in the central region (|η γ | T γ 5.0 GeV and lepton-photon angular separation ΔR ell γ > 0.7, eight electron W γ candidates were observed. From these events, the production cross section times decay branching ratio for the electron sample was measured to be a σ · B(W γ ) exp = 17.0 -13.4 +13.6 (stat. + syst.)pb. The W γ cross section is sensitive to the anomalous couplings of the W boson. Using the W γ cross section measurement, the absence of an excess of large E T photons accompanying the production of a W boson enables one to obtain direct limits on anomalous WW γ couplings. The experimental limits on the anomalous couplings was measured to be -7.2 W ≥ 1 TeV for saturation of unitarity, corresponding to probing a distance scale of order L W ≤ 2.0 x 10 -4 fm. The experimental limits on anomalous WW γ couplings place bounds on the higher-order electromagnetic moments of the W boson -- the magnetic dipole and electric quadrupole moments and the W boson mean-squared charge radius. The experimental results presented in this thesis are in good agreement with Standard Model expectations

  15. A multienzyme complex channels substrates and electrons through acetyl-CoA and methane biosynthesis pathways in Methanosarcina.

    Directory of Open Access Journals (Sweden)

    Dillon J Lieber

    Full Text Available Multienzyme complexes catalyze important metabolic reactions in many organisms, but little is known about the complexes involved in biological methane production (methanogenesis. A crosslinking-mass spectrometry (XL-MS strategy was employed to identify proteins associated with coenzyme M-coenzyme B heterodisulfide reductase (Hdr, an essential enzyme in all methane-producing archaea (methanogens. In Methanosarcina acetivorans, Hdr forms a multienzyme complex with acetyl-CoA decarbonylase synthase (ACDS, and F420-dependent methylene-H4MPT reductase (Mer. ACDS is essential for production of acetyl-CoA during growth on methanol, or for methanogenesis from acetate, whereas Mer is essential for methanogenesis from all substrates. Existence of a Hdr:ACDS:Mer complex is consistent with growth phenotypes of ACDS and Mer mutant strains in which the complex samples the redox status of electron carriers and directs carbon flux to acetyl-CoA or methanogenesis. We propose the Hdr:ACDS:Mer complex comprises a special class of multienzyme redox complex which functions as a "biological router" that physically links methanogenesis and acetyl-CoA biosynthesis pathways.

  16. Safety analysis report for the Neutron Multiplier Facility, 329 Building

    International Nuclear Information System (INIS)

    Rieck, H.G.

    1978-09-01

    Neutron multiplication is a process wherein the flux of a neutron source such as 252 Cf is enhanced by fission reactions that occur in a subcritical assemblage of fissile material. The multiplication factor of the device depends upon the consequences of neutron reactions with matter and is independent of the initial number of neutrons present. Safe utilization of such a device demands that the fissile material assemblage be maintained in a subcritical state throughout all normal and credibly abnormal conditions. Examples of things that can alter the multiplication factor (and degree of subcriticality) are temperature fluctuations, changes in moderator material such as voiding or composition, addition of fissile materials, and change in assembly configuration. The Neutron Multiplier Facility (NMF) utilizes a multiplier- 252 Cf assembly to produce neutrons for activation analysis of organic and inorganic environmental samples and for on-line mass spectrometry analysis of fission products which diffuse from a stationary fissile target (less than or equal to 4 g fissile material) located in the Neutron Multiplier. The NMF annex to the 329 Building provides close proximity to related counting equipment, and delay between sample irradiation and counting is minimized

  17. Neutron fluctuations in a multiplying medium randomly varying in time

    Energy Technology Data Exchange (ETDEWEB)

    Pal, L. [KFKI Atomic Energy Research Inst., Budapest (Hungary); Pazsit, I. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Nuclear Engineering

    2006-07-15

    The master equation approach, which has traditionally been used for the calculation of neutron fluctuations in multiplying systems with constant parameters, is extended to a case when the parameters of the system change randomly in time. A forward type master equation is considered for the case of a multiplying system whose properties jump randomly between two discrete states, both with and without a stationary external source. The first two factorial moments are calculated, including the covariance. This model can be considered as the unification of stochastic methods that were used either in a constant multiplying medium via the master equation technique, or in a fluctuating medium via the Langevin technique. The results obtained show a much richer characteristic of the zero power noise than that in constant systems. The results are relevant in medium power subcritical nuclear systems where the zero power noise is still significant, but they also have a bearing on all types of branching processes, such as evolution of biological systems, spreading of epidemics etc, which are set in a time-varying environment.

  18. Neutron fluctuations in a multiplying medium randomly varying in time

    International Nuclear Information System (INIS)

    Pal, L.; Pazsit, I.

    2006-01-01

    The master equation approach, which has traditionally been used for the calculation of neutron fluctuations in multiplying systems with constant parameters, is extended to a case when the parameters of the system change randomly in time. A forward type master equation is considered for the case of a multiplying system whose properties jump randomly between two discrete states, both with and without a stationary external source. The first two factorial moments are calculated, including the covariance. This model can be considered as the unification of stochastic methods that were used either in a constant multiplying medium via the master equation technique, or in a fluctuating medium via the Langevin technique. The results obtained show a much richer characteristic of the zero power noise than that in constant systems. The results are relevant in medium power subcritical nuclear systems where the zero power noise is still significant, but they also have a bearing on all types of branching processes, such as evolution of biological systems, spreading of epidemics etc, which are set in a time-varying environment

  19. Studies on electron reconstruction and top quark pair production cross-section measurement in di-leptonic channels in the ATLAS experiment at LHC

    International Nuclear Information System (INIS)

    Theveneaux-Pelzer, Timothee

    2012-01-01

    The LHC produced proton-proton collision data with 7 TeV of center of mass energy corresponding to an integrated luminosity of 40 pb -1 in 2010 and of 5 fb -1 in 2011. The data collected by ATLAS have led to the validation the understanding of the detector, to the evaluation of its performance and to many measurements of physical quantities. In this context the top quark is a privileged field of study for TeV scale physics as well as for performance studies. After a reminder of the phenomenology of the standard model the first part of this thesis is devoted to the description of the detector and in particular of the liquid argon calorimeters for which the influence of the variations of the high voltage values is detailed. The second part is focused on studies about the reconstruction and the identification of electrons conducted on simulated data, but also on 2010 collision data thanks to J/ψ → e + e - events with the tag-and-probe method. The last part is devoted to top quark studies. A description of the signal and background simulated data for tt-bar events is given, as are the reconstruction and identification procedures of the objects present in the final state. The estimation of the contribution of events with a mis-identified lepton thanks to the matrix-method is then presented before the measurement of the tt-bar cross-section in dilepton channels made on 2011 data: the value of 178.8 ±2.3 (stat) +8. 9 -8. 4 (sys) +8.0 -7.4 (lumi) pb obtained by combining the three channels is compatible with theoretical predictions. (author) [fr

  20. Studies on electron reconstruction and top quark pair production cross-section measurement in dileptonic channels in the ATLAS experiment at LHC

    International Nuclear Information System (INIS)

    Theveneaux-Pelzer, T.

    2012-01-01

    The LHC produced proton-proton collision data with 7 TeV of center of mass energy corresponding to an integrated luminosity of 40 pb -1 in 2010 and of 5 fb -1 in 2011. The data collected by ATLAS have led to the validation of the understanding of the detector, to the evaluation of its performance and to many measurements of physical quantities. In this context the top quark is a privileged field of study for TeV scale physics as well as for performance studies. After a reminder of the phenomenology of the standard model the first part of this thesis is devoted to the description of the detector and in particular of the liquid argon calorimeters for which the influence of the variations of the high voltage values is detailed. The second part is focused on studies about the reconstruction and the identification of electrons conducted on simulated data, but also on 2010 collision data thanks to J/ψ → e + e - events with the tag-and-probe method. The last part is devoted to top quark studies. A description of the signal and background simulated data for tt-bar events is given, as are the reconstruction and identification procedures of the objects present in the final state. The estimation of the contribution of events with a mis-identified lepton thanks to the matrix-method is then presented before the measurement of the tt-bar cross-section in dilepton channels made on 2011 data: the value of [178.8 ± 2.3 (stat) +8.9-8.4 (syst) +8.0-7.4 (lumi)] pb obtained by combining the three channels is compatible with theoretical predictions. (author)