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Computational Approach for Evaluation of Nuclear Data IincludingCovariance Information
A. Yu. Konobeyev,U. Fischer,P. E. Pereslavtsev 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
A computational approach was developed for the evaluation of nuclearcross-section data taking into account experimental data and results ofnuclear model calculations. A set of computer programs, called BEKED, wasdeveloped to perform the processing of experimental data, provide the runsfor the cross-section and covariance data calculations, and perform theglobal evaluation of nuclear data. The calculation of covariances arecarried out using different approaches including the generalizedleast-squares method and the Monte Carlo method developed by D.Smith, whichtakes into account both experimental and nuclear model uncertainties.Presently, the BEKED approach integrates the nuclear model codes TALYS andALICE/AS, as well as other codes employing e.g. the intranuclear cascadeevaporation model.
Human Areas V3A and V6 Compensate for Self-Induced Planar Visual Motion
Fischer, E.,Bulthoff, Heinrich H.,Logothetis, Nikos K.,Bartels, A. Cell Press 2012 Neuron Vol.73 No.6
Little is known about mechanisms mediating a stable perception of the world during pursuit eye movements. Here, we used fMRI to determine to what extent human motion-responsive areas integrate planar retinal motion with nonretinal eye movement signals in order to discard self-induced planar retinal motion and to respond to objective (''real'') motion. In contrast to other areas, V3A lacked responses to self-induced planar retinal motion but responded strongly to head-centered motion, even when retinally canceled by pursuit. This indicates a near-complete multimodal integration of visual with nonvisual planar motion signals in V3A. V3A could be mapped selectively and robustly in every single subject on this basis. V6 also reported head-centered planar motion, even when 3D flow was added to it, but was suppressed by retinal planar motion. These findings suggest a dominant contribution of human areas V3A and V6 to head-centered motion perception and to perceptual stability during eye movements.
U. Fischer,P. Batistoni,E. Dupont,R. A. Forrest,H. Hendrikson,J. Izquierdo,J. -C. Sublet 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
An overview is presented of the European Fusion File (EFF) and the European Activation File (EAF) efforts which aim at developing qualified nuclear data bases and validated computational tools for nuclear calculations of fusion systems tailored to the specific needs of the European fusion programme. The related tasks are conducted in the frame of the Fusion for Energy (F4E) work programme and are devoted to the evaluation, processing, testing and benchmarking of required nuclear cross section and uncertainty data, the development of computational tools for sensitivity/uncertainty calculations, and to conduct integral benchmark experiments exploiting also new measurement techniques. The data evaluations are integrated into the Joint Evaluated Fission and Fusion File (JEFF) after having passed a series of qualification tests including their validation through computational analyses of integral benchmark experiments.
Status of the JEFF Nuclear Data Library
A. J. Koning,E. Bauge,C. J. Dean,E. Dupont,U. Fischer,R. A. Forrest,R. Jacqmin,H. Leeb,M. A. Kellett,R. W. Mills,C. Nordborg,M. Pescarini,Y. Rugama,P. Rullhusen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The status of the Joint Evaluated Fission and Fusion file (JEFF) is described. Recently, the JEFF-3.1.1 nuclear data library was released and shortly after adopted by the French nuclear power industry for inclusion in their production and analysis codes. Recent updates include actinide evaluations, materials evaluations that have emerged from various European nuclear data projects, the activation library, the decay data and fission yield sub-libraries, and fusion-related data files from the European F4E project. The revisions were motivated by the availability of new measurements, modelling capabilities and trends from integral experiments. Validations have been performed, mainly for criticality, reactivity temperature coefficients, fuel inventory, decay heat and shielding of thermal and fast systems. The next release of the library, JEFF-3.2, will be discussed. This will contain among others a significant increase of covariance data evaluations, modern evaluations for various structural materials, a larger emphasis on minor actinides and addition of high-quality gamma production data for many fission products.
Spectral Flux of the p-^7Li(C) Q-M Neutron Source Measured by Proton Recoil Telescope
J. Novak,P. Bem,M. Gotz,M. Honusek,E. Simeckova,M. Stefanik,U. Fischer,S. P. Simakov 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The cyclotron-based fast neutron source at NPI produces mono-energetic neutron fields up to 35 MeV neutron energy using the p+^7Li(carbon backing) reactions. To be applied for activation cross-section measurements, not only the intensity of neutron peak, but also the contribution of low-energy continuum in the spectra must be well determined. Simulations of the spectral flux from present source at a position of irradiated samples were performed using CYRIC TOF-data validated in the present work against LA150h by calculations with the transport Monte Carlo code MCNPX. Simulated spectra were tested by absolute measurements using a proton-recoil telescope technique. The recoil-proton spectrometer consisted of a shielded scattering chamber with polyethylene and carbon radiators and the ΔE_1-ΔE_2-E telescope of silicon-surface detectors located to the neutron beam axis at 45˚ in the laboratory system. Si-detectors were handled by usual data acquisition system. Dead-time - and pulse-overlap losses of events were determined from the count rate of pulse generator registered during duty cycle of accelerator operation. The proton beam charge and data were taken in the list mode for later replay and analysis. The calculations for ^7Li(p,n) and ^(12)C(p,n) reactions reasonably reproduce CYRIC TOF neutron source spectra. The influence of neutron source set-up (proton beam dimensions, ^7Li-foil, carbon stopper, cooling medium, target support/chamber and the geometry-arrangement of irradiated sample) on the spectral flux is discussed in details.
The Measurement of Neutron Activation Cross Section of ^(59)Co Below 36 MeV
E. Simeckov,P. Bem,V. Burjan,M. Gotz,M. Honusek,V. Kroha,J. Novak,U. Fischer,S. P. Simakov,R. A. Forrest 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
An accurate knowledge of the cross section for neutron-induced reactions on ^(59)Co is of importance due to use of cobalt as a structural material in fission and fusion reactors, its applicability in neutron dosimetry and for testing theoretical models as well. The thin Co foils (0.25 mm thickness, 99.9% purity, Goodfellow product) were irradiated in the quasi-momoenergetic p-Li neutron field. For the production of the neutron fields, the proton beam from the NPI energy-variable cyclotron U120M at proton energies 19.8, 25.1, 27.6, 30.1, 32.7, 35.0, and 37.4 MeV and thin ^7Li target with carbon stopper were used. The reaction ^7Li(p,n) produces the high-energy quasi-monoenergetic neutrons with tail to lower energies. The flux density and neutron spectra were evaluated by MCNPX code using ^7Li(p,n) cross section measurement of other authors and including correction to the NPI target layout. The time profile of the neutron source strength during the irradiation was monitored by the proton beam current on the neutron-source target, recorded by a calibrated current-to-frequency converter on a PC. Au foils were used as additional monitors. The foil activity determination was performed by the nuclear spectrometry method employing two calibrated HPGe detectors of 23 and 50% efficiency and of FWHM (Full Width Half Maximum) 1.8 keV at 1.3 MeV for gamma-ray measurement. The reaction rates for ^(59)Co(n,p)^(59)Fe, ^(59)Co(n,α)^(56)Mn, ^(59)Co(n,2nα)^(54)Mn, ^(59)Co(n,3n)^(57)Co, ^(59)Co(n,2n)^(58m)Co, and ^(59)Co(n,2n)^(58g)Co were obtained. Integral activation cross sections were estimated. The preliminary results are discussed.
On Low and Medium Energy Deuteron-Induced Reactions on ^(63,65)Cu
E. Simeckov,P. Bem,M. Honusek,L. Zavorka,U. Fischer,S. P. Simakov,R. A. Forrest,M. Avrigeanu,V. Avrigeanu,F. L. Roman 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The activation cross sections of (d,p), (d,2n), (d,3n), and (d,2p) reactions on ^(63,65)Cu were measured in the energy range from 4 to 20 MeV using the stacked-foils technique. Errors of present experimental cross section data are composed of the scale factor (∼5%, due to energy and beam current uncertainty) and datum uncertainty of the foil thickness (∼2%) and a mean statistical error in the determination of specific activities (∼3%). Following a previous extended analysis of elastic-scattering, breakup and direct-reaction of deuterons on light nuclei, for energies from 3 to 60 MeV, the pre-equilibrium and statistical emissions are considered in the same energy range. Finally, all available deuteron-induced reaction cross sections for <sup>63,65</sup>Cu have been involved within a simultaneous analysis of the deuteron elastic-scattering and reaction data.