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Two main developments in neutron Fourier time-of-flight (TOF) are presented. The first is a new sinusoidal stator design that eliminates a systematic effect associated with triangular modulation in existing Fourier choppers. Despi...
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Two main developments in neutron Fourier time-of-flight (TOF) are presented. The first is a new sinusoidal stator design that eliminates a systematic effect associated with triangular modulation in existing Fourier choppers. Despite sinusoidal modulation being associated with a reduction in average beam transmission, it is mathematically demonstrated that, on average and for good signal-to-background, only about 3 % additional measurement time is required to achieve equal statistical uncertainty. The second development is a new method to measure the chopper phase offset. This method relies only on symmetries inherent to the Fourier transform of any physical TOF spectrum.
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An accurate method to detect obstacles and dangerous areas is the key to the safe performance of autonomous robots. Time of flight sensors can report their existence through the emission, reflection, and measurement of wave patter...
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An accurate method to detect obstacles and dangerous areas is the key to the safe performance of autonomous robots. Time of flight sensors can report their existence through the emission, reflection, and measurement of wave patterns, but large wavelength light projection is often unreliable in outdoors environments, due to solar radiation contamination. In this paper, a specific Microsoft Kinect arrangement on a robotic vehicle is proposed, such that outdoors detection is possible. The main contribution of this paper is the description of a sequence of filtering techniques, which translate the depth image provided by the sensor into definite obstacle projections in the navigability map used by the vehicle. A series of experiments proves that the Kinect device is more accurate at detecting obstacles using this procedure than a camera pair using two different stereovision techniques.
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We show first results of an analysis of the dynamics of water as observed by neutron scattering, based on a model common to both isotopic forms, H_2O and D_2O. Using incoherent scattering results from H_2O, and the liquid structur...
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We show first results of an analysis of the dynamics of water as observed by neutron scattering, based on a model common to both isotopic forms, H_2O and D_2O. Using incoherent scattering results from H_2O, and the liquid structure factor of D_2O, we show that within the framework of an approximation of decoupled motions, the H_2O and D_2O spectra can be reproduced in a broad wave-vector range with physical parameters very similar for both kinds of water.
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摘要 :
We show first results of an analysis of the dynamics of water as observed by neutron scattering, based on a model common to both isotopic forms, H_2O and D_2O. Using incoherent scattering results from H_2O, and the liquid structur...
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We show first results of an analysis of the dynamics of water as observed by neutron scattering, based on a model common to both isotopic forms, H_2O and D_2O. Using incoherent scattering results from H_2O, and the liquid structure factor of D_2O, we show that within the framework of an approximation of decoupled motions, the H_2O and D_2O spectra can be reproduced in a broad wave vector range with physical parameters very similar for both kinds of water.
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The expressions describing the time-of-flight (TOF) and conditions of TOF focusing of ion packets by energies in the ion source with two accelerating gaps have been obtained. The first gap is the ionization region with a uniform e...
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The expressions describing the time-of-flight (TOF) and conditions of TOF focusing of ion packets by energies in the ion source with two accelerating gaps have been obtained. The first gap is the ionization region with a uniform electrostatic field, whereas the second gap is the immersion objective with a non-uniform electrostatic field, where the role of the "cathode" (emitting surface) is played by the exit window of the ionization region.
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Self-localization of smart portable devices serves as foundation for several novel applications. This work proposes a set of algorithms that enable a mobile device to passively determine its position relative to a known reference ...
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Self-localization of smart portable devices serves as foundation for several novel applications. This work proposes a set of algorithms that enable a mobile device to passively determine its position relative to a known reference with centimeter precision, based exclusively on the capture of acoustic signals emitted by controlled sources around it. The proposed techniques tackle typical practical issues such as reverberation, unknown speed of sound, line-of-sight obstruction, clock skew, and the need for asynchronous operation. After their theoretical developments and off-line simulations, the methods are assessed as real-time applications embedded into off-the-shelf mobile devices operating in real scenarios. When line of sight is available, position estimation errors are at most 4 cm using recorded signals.
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This paper reflects on the historical development of orthogonal acceleration time-of-flight analyzers that have been used routinely for high sensitivity analyses of biological molecules for more than a decade. In particular, the r...
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This paper reflects on the historical development of orthogonal acceleration time-of-flight analyzers that have been used routinely for high sensitivity analyses of biological molecules for more than a decade. In particular, the role of the late Michael Guilhaus from the University of New South Wales in Australia is highlighted. This account shows that like most advances in science, successful commercialization of new technology is not straightforward and is often the result of critical contributions of different people and organizations at different points in time.
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We present in this paper a study of the Alice-TOF Multigap Resistive Plate Chamber (MRPC) performance by using several gas mixtures. We also present a search for possible ageing effects, by studying two MRPCs irradiated at the CER...
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We present in this paper a study of the Alice-TOF Multigap Resistive Plate Chamber (MRPC) performance by using several gas mixtures. We also present a search for possible ageing effects, by studying two MRPCs irradiated at the CERN Gamma Irradiation Facility.
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Several benchmark experiments performed in the past using the time-of-flight technique are stored in the SIN-BAD database distributed by the Nuclear Energy Agency Data Bank (e.g., OKTAVIAN, FNS, and IPPE benchmarks). These benchma...
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Several benchmark experiments performed in the past using the time-of-flight technique are stored in the SIN-BAD database distributed by the Nuclear Energy Agency Data Bank (e.g., OKTAVIAN, FNS, and IPPE benchmarks). These benchmarks proved to be useful for the validation of the computer codes and nuclear data evaluations, but some expertise is required from the users for the proper modeling and interpretation of the problems. The iron spheres experiment carried out in the 14-MeV facility at IPPE, Obninsk, Russia, was proposed as one of the problems in the scope of the Coordinated Network for Radiation Dosimetry (CONRAD) project sponsored by the European Commission within its 6th Framework Programme. The objective was to test the skills of the participants in the use of the computer codes and the nuclear data but also to obtain feedback information on how suitable the information contained in SINBAD is for the nowadays users and the computer codes. Outcomes of the intercomparison provide guidance for the future compilations in order to facilitate the use of the experimental data.
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In the collisions of 20q keV Ar~(q+) with C_(60), the relative cross-section for the production of higher charge of C_(60)~(r+) increases with the initial charge state of the projectiles increasing. By comparing the TOF spectra pr...
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In the collisions of 20q keV Ar~(q+) with C_(60), the relative cross-section for the production of higher charge of C_(60)~(r+) increases with the initial charge state of the projectiles increasing. By comparing the TOF spectra produced by 56 keV and 160 keV Ar~(8+) ion impact, respectively, we found that the intensity of the fragments C_((60-2n))~(r+) via evaporation at higher energy was much less.
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