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  • 1
    Electronic Resource
    Electronic Resource
    A flexible implementation of scanning tunneling spectroscopy utilizing C-language on the personal computer (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 3646-3651 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Scanning tunneling spectroscopy (STS) capable of measuring the local density of states dI/dV=G(V,x,y) correlated with the topography z(x,y) is implemented on a PC/AT computer system. An algorithm using dimensional decoupling and recursive linking is incorporated in a compact C-language code to achieve flexible and sophisticated STS control. Data acquisition and processing methods which provide the local density of states G(V,x,y,s) at different tip heights s in registry with z(x,y) are described. Examples of novel low-temperature experiments are given to show the capabilities of this implementation of STS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143591
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  • 2
    Electronic Resource
    Electronic Resource
    Material-enhanced spatially dependent etch rate of SiO2 in CF4 reactive ion etching (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 2319-2321 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the spatially dependent enhanced etch rate of SiO2 in a CF4 planar reactive ion etcher due to the presence of the compounds GaAs or InP, or the single elements Ti, V, Nb, Ta, Cr, Mo, W, Ni, Pd, Pt, Cu, Ag, Au, Al, Ga, In, or Ge. The etch rate enhancement is maximum immediately adjacent to the source of the material and decreases nonlinearly with increasing distance away from the source of the material. Of the materials studied, the largest local etch rate increase was due to the element Ni (65% increase), followed closely by the elements In (57%) and Ga (43%) and the compounds InP (55%) and GaAs (40%). The lateral range of the effect extends 5 to 30 mm away from the material depending on the element or compound. Material interaction, possibly a catalized reaction, with the CF4 plasma reactants and lateral transport to provide an increased local concentration of fluorine at the SiO2 surface is a preliminary suggestion for the observed etch rate increase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102930
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  • 3
    Electronic Resource
    Electronic Resource
    Etch masks for microfabrication produced by electron beam sublimation of graphitic carbon deposited as semimetallic amorphous carbon thin films (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 2045-2047 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High quality etch masks for nanometer plasma processing can be formed from thin films of semimetallic amorphous carbon that are deposited by electron beam sublimation of graphitic carbon. These films are amorphous, hard, semimetallic, and mirror-reflective. These electron beam sublimation deposited (EBSD) semimetallic amorphous carbon (semimetallic a-C) thin films can be routinely deposited up to at least 400 nm thick and patterned by SF6 plasma reactive ion etching (RIE) via standard photoresist masks. They are demonstrated to be excellent etch masks on gallium arsenide, silicon, and germanium substrates using chemically assisted ion beam etching (CAIBE), also known as ion beam assisted etching (IBAE), reactive ion beam etching (RIBE), and RIE. The carbon etch masks have fine grain, low chemical reactivity, low sputter rates, and high thermal stability. Finally, the EBSD semimetallic a-C can be readily stripped by SF6 or O2 or H2 plasmas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108355
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  • 4
    Electronic Resource
    Electronic Resource
    Simulation of the Effect of Synapses: the Significance of the Dendritic Diameter in Impulse Propagation (1992)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 4 (1992), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The effectiveness of synapses at various sites of the dendritic tree was studied using a segmental cable model with a program developed by Hines (Int. J. Biomed. Comput., 24, 55–68, 1989). The model rendered possible a high-fidelity simulation of the dendritic geometry of a frog motoneuron described in the accompanying paper (Birinyi et al., Eur. J. Neurosci., 1003–1012, 1992). The model was used in the passive membrane mode and the synaptic activity was simulated with current injections into large and small diameter dendrites at proximal and distal locations. Synaptic efficiency was defined by the charge transfer ratio expressed as the proportion of the injected current which appeared at the soma. The charge transfer ratio was determined with uniform and non-uniform distribution of specific membrane resistance over the soma–dendrite surface while the diameter of selected dendrite segments changed. The best charge transfer ratio was found with the largest dendrite membrane resistance, and the maximum efficiency of synaptic activity appeared at the original size of the dendrite segment stimulated. The amount of current that flowed in the proximal and distal directions from the segment stimulated depended on the diameter of that segment. The increase in diameter of proximal dendrites increased synaptic efficiency on distal dendrites, whereas the reverse caused a decline in synaptic efficiency on proximal dendrites. In addition to the diameter of dendrites, the arborization pattern also played a significant role in this mechanism. It is concluded that the cellulipetal increase in dendrite diameter greatly increases synaptic efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1992.tb00128.x
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  • 5
    Electronic Resource
    Electronic Resource
    The Extent of the Dendritic Tree and the Number of Synapses in the Frog Motoneuron (1992)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 4 (1992), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Frog motoneurons were intracellularly labelled with cobaltic lysine in the brachial and the lumbar segments of the spinal cord, and the material was processed for light microscopy in serial sections. With the aid of the neuron reconstruction system NEUTRACE, the dendritic tree of neurons was reconstructed and the length and surface area of dendrites measured. The surface of somata was determined with the prolate – oblate average ellipsoid calculation. Corrections were made for shrinkage and for optical distortion. The mean surface area of somata was 6710 μm2; lumbar motoneurons were slightly larger than brachial motoneurons. The mean length of the combined dendritic tree of brachial neurons was 29 408 μm and that of lumbar neurons 46 806 μm. The mean surface area was 127 335 μm2 in brachial neurons, and 168 063 μm2 in lumbar neurons. The soma – dendrite surface area ratio was 3 – 5% in most cases. Dendrites with a diameter of ≤ 1.0 μm constituted ∼ 75% of the combined dendritic length in most of the neurons. Unlike in the cat, there was no correlation between the size of stem dendrites and the extent of daughter branches. From the synaptic density estimated in earlier electron microscope investigations of frog motoneuron dendrites (Antal et al., J. Neurocytol., 15, 303–310, 1986; 21, 34–49, 1992), and from the present data, the number of synapses on the dendritic tree was calculated. The calculations indicated 26 949 synapses on the smallest and 61 519 synapses on the largest neuron if the synaptic density was multiplied by the length of the dendritic tree. If the synaptic density was multiplied by the surface area of the dendritic tree the calculation yielded 23 337 synapses for the smallest and 60 682 synapses for the largest neuron. More than 60% of the combined surface area of dendrites was 〉600 μm from the soma. This suggests that about two-thirds of the synapses impinged upon distant dendrites 〉600 μm from the soma. The efficacy of synapses at these large distances is investigated on model neurons in the accompanying paper (Wolf et al., Eur. J. Neurosci., 4, 1013–1021, 1992).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1992.tb00127.x
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  • 6
    Electronic Resource
    Electronic Resource
    Triple Regge analysis of inclusiveΛ production inK + p and π+ p interactions at 250 GeV/c (1991)
    Springer
    The European physical journal 49 (1991), S. 235-238 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A triple Regge analysis is performedof inclusive Λ production in the proton fragmentation region ofK +→Λ+X and π+→Λ+X at 250 GeV/c. Slope and intercept of the leading strange meson trajectory are determined. The results obtained here are compared with those of other experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01555495
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  • 7
    Electronic Resource
    Electronic Resource
    Collective characteristics of hadron systems produced in beam fragmentation of π+ p collisions at 250 GeV/c (1991)
    Springer
    The European physical journal 49 (1991), S. 367-374 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Collective characteristics are studied of hadrons produced in beam fragmentation of non-single-diffractive π+ p-interactions at 250 GeV/c. An attempt is made to obtain experimental information on the properties of leading cluster production and fragmentation. On average, the leading cluster carries 0.8±0.1 of the incident momentum, so that the mean value of the inelasticity coefficient of 〈k〉=0.2±0.1 is significantly smaller than that deduced from leading single hadron spectra. The momentum transfer distribution shows that nonsingle-diffractive processes are less peripheral than diffraction dissociation. The analysis of thrust and sphericity shows jet-like structure of pion fragmentation, that of the charge flow an average forward charge of 〈Q f 〉=0.45±0.04, in agreement with the average charge of the beam valence quarks. Our data are compared to diffraction dissociation and to the Fritiof model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01549688
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  • 8
    Electronic Resource
    Electronic Resource
    Bose-Einstein correlations inpp collisions at 400 GeV/c (1992)
    Springer
    The European physical journal 54 (1992), S. 21-32 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Bose-Einstein correlations among identically charged pions produced inpp collisions at 400 GeV/c are studied using the EHS spectrometer. Empoying the Kopylov-Podgoretskii parametrization, the average size of the emitting regionr k and its lifetime τ for pion production were determined to ber k=1.71±0.04 fm andcτ=0.89±0.05fm. The average sizer g in terms of the Lorentz invariant Goldhaber parametrization was determined to ber g=1.20±0.03fm. A decrease of the size with increasing momentum of the pions was observed. The size and the incoherence parameter of the pion emitting region were determined as a function of the charged particle multiplicity and the momentum of the pions. Identified charged kaons were used to study Bose-Einstein correlations among identically charged kaonsK ±K±. The average size of the emitting region for kaon production was determined to ber k=1.87±0.33fm in terms of the Kopylov-Podgoretskii parametrization. A study of the influence of a reference sample is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01881705
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  • 9
    Electronic Resource
    Electronic Resource
    Study of intranuclear collision effects in interactions ofK +/π + mesons with Al and Au nuclei at 250 GeV/c (1992)
    Springer
    The European physical journal 56 (1992), S. 371-380 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Multiplicity, inclusive, correlation and collective characteristics of multiparticle production processes inK + Al,K + Au, π+ Al and π+ Au interactions at 250 GeV/c are studied with the European Hybrid Spectrometer, providing high statistics and almost 4 π acceptance for final state charged particles. It is shown that the proton energy spectrum practically does not depend on the target atomic weight, but the proton angular distributions reveal a strongA-dependence. In a model independent way, the average number of intranuclear collisions is extracted, and it is shown that their dominant part (60% for Al and 80% for Au) is caused by interactions of the non-leading particles produced in the target fragmentation. The multiplication ratio of the produced particles for the Au nucleus changes fromR≃40 at the smallest rapidities in the target fragmentation region, down toR=0.37±0.06 at the largest rapidities in the beam fragmentation region. It is found that the average total longitudinal momentum of the charged products of the beam fragmentation depends weakly on the number of leading hadron (cluster) intranuclear collisions which are characterized by a low inelasticity coefficient 〈k〉=0.17±0.03.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01565944
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  • 10
    Electronic Resource
    Electronic Resource
    A study of double pomeron exchange inπ + p andK + p interactions at 250 GeV/c (1991)
    Springer
    The European physical journal 50 (1991), S. 353-360 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Quasi-elastic scattering with central dipion cluster production is studied in π+ p andK + p interactions at 250 GeV/c. The cross section of double pomeron exchange is obtained as σDPE(π+ p →π+(π+π−)p)=24 ±5 µb and σDPE(K + p→K +(π+π−)p)=19 ±5 µb. The low energy pomeron-pomeron cross section is estimated for the first time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01551447
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