Prompt Neutron

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Cheol Ho Pyeon - One of the best experts on this subject based on the ideXlab platform.

Takaaki Ohsawa - One of the best experts on this subject based on the ideXlab platform.

  • determination of Prompt Neutron decay constant from phase shift between beam current and Neutron detection signals for an accelerator driven system in the kyoto university critical assembly
    Journal of Nuclear Science and Technology, 2015
    Co-Authors: Atsushi Sakon, Cheol Ho Pyeon, Kengo Hashimoto, Sinya Hohara, Tadafumi Sano, Wataru Sugiyama, Takahiro Yagi, Takaaki Ohsawa
    Abstract:

    A unique power spectral analysis for a subcritical reactor system driven by a pulsed 14 MeV Neutron source was carried out at the Kyoto University Critical Assembly (KUCA). In this analysis, a complex cross-power spectral density between time-sequence signal data from an accelerator beam ammeter and a Neutron detector was measured to determine the Prompt-Neutron decay constant of an accelerator-driven system (ADS) from the phase data of the spectral density. Assuming the one-point kinetics model, in theory, the decay constant can be arithmetically derived from the phase at the integral multiples of the pulse repetition frequency. However, the actual derivation from the phase at a pulse repetition frequency of 20 Hz considerably underestimated the Prompt-Neutron decay constant, compared with that obtained by a previous pulsed Neutron experiment, and the derived decay constant apparently decreased with an increase in the multiple of the pulsed repetition frequency. Considering a lag time in detector respons...

  • power spectral analysis for a thermal subcritical reactor system driven by a pulsed 14 mev Neutron source
    Journal of Nuclear Science and Technology, 2013
    Co-Authors: Atsushi Sakon, Cheol Ho Pyeon, Tsuyoshi Misawa, Kengo Hashimoto, Tadafumi Sano, Wataru Sugiyama, Hiroshi Taninaka, Hironobu Unesaki, Takaaki Ohsawa
    Abstract:

    A series of power spectral analyses for a thermal subcritical reactor system driven by a pulsed 14 MeV Neutron source was carried out at Kyoto University Critical Assembly (KUCA), to determine the Prompt-Neutron decay constant of the accelerator-driven system (ADS). The cross-power spectral density between time-sequence signal data of two Neutron detectors was composed of a familiar continuous reactor noise component and many delta-function-like peaks at the integral multiple of pulse repetition frequency. The Prompt-Neutron decay constant inferred from the reactor noise component of the cross-power spectral density was consistent with that obtained by a pulsed Neutron experiment. However, the reactor noise component of the auto-power spectral density of each detector was hidden by a white chamber noise in the higher-frequency range and this feature resulted in a considerable underestimation of the decay constant. For several runs with a low pulse-repetition frequency, furthermore, we attempted to infer t...

  • feynman α analysis for a thermal subcritical reactor system driven by an unstable 14mev Neutron source
    Journal of Nuclear Science and Technology, 2011
    Co-Authors: Hiroshi Taninaka, Cheol Ho Pyeon, Tsuyoshi Misawa, Kengo Hashimoto, Tadafumi Sano, Wataru Sugiyama, Atsuko Miyoshi, Takaaki Ohsawa
    Abstract:

    In a series of Feynman-α correlation measurements for a thermal Accelerator-Driven System (ADS) with 14MeV Neutrons at the Kyoto University Critical Assembly (KUCA), an unstable accelerator condition such as a drift of beam current has been frequently observed. Neutron source instability caused by such unavoidable beam-current instability resulted in a divergent variance-to-mean ratio and, consequently, the correlation analysis failed. Nevertheless, we attempted to apply a difference-filtering technique to the correlation analysis to reduce the influence of the above instability. The present attempt resulted in consistent Prompt-Neutron decay constants with those obtained in a previous pulsed Neutron experiment. The application of the filtering is expected to enhance the robustness of Feynman-α analysis against various instabilities of accelerator operation in actual ADS.

  • determination of lambda mode eigenvalue separation of a thermal accelerator driven system from pulsed Neutron experiment
    Journal of Nuclear Science and Technology, 2010
    Co-Authors: Hiroshi Taninaka, Cheol Ho Pyeon, Tsuyoshi Misawa, Kengo Hashimoto, Tadafumi Sano, Takaaki Ohsawa
    Abstract:

    Basic research on the Accelerator-Driven System (ADS) with thermal Neutron spectrum has been promoted by the Kyoto University Research Reactor Institute. At the Kyoto University Critical Assembly (KUCA), various experiments on thermal ADS with a pulsed spallation source are planned. In such an ADS, Neutron flux distribution may be sensitive to the injection of Neutrons, and the high sensitivity results in various spatial effects. In this study, a pulsed Neutron experiment with 14MeV Neutrons was carried out in a thermal ADS of KUCA, to determine the λ-mode eigenvalue separation, which is a quantitative indication of spatial effects. An original data-processing technique was applied to infer Prompt-Neutron decay constants of fundamental and higher modes from Neutron count decay data, and then the eigenvalue separation around 13%Δk/k was obtained from these decay constants.

Anabella Tudora - One of the best experts on this subject based on the ideXlab platform.

  • Inclusion of sequential emission into the most probable fragmentation approach (Los Alamos model) and its validation
    'Springer Science and Business Media LLC', 2020
    Co-Authors: Anabella Tudora
    Abstract:

    A new version of the Los Alamos (LA) model, based on more physical considerations than the previous versions by taking into account the sequential emission of Prompt Neutrons, is proposed. A residual temperature distribution for each emission sequence P$$_{\mathrm {k}}$$(T) is considered, so that this new version can provide the Prompt Neutron spectrum in the center-of-mass and laboratory frames of each Neutron successively emitted from the light and heavy fragment. The LA model with sequential emission is applied on 15 fission cases which were not included in the 49 cases used in the elaboration of the systematics of different quantities of residual nuclei, on which the general form of $$\hbox {P}_{\mathrm {k}}$$(T) is based. The good description of experimental Prompt Neutron spectrum data of these fission cases by the model results constitutes a relevant validation of the LA model with sequential emission. Systematic behaviours of the average energies (in the center-of-mass and laboratory frames) provided by this model for each Neutron sequentially emitted, are also emphasized

  • revisiting the residual temperature distribution in Prompt Neutron emission in fission
    European Physical Journal A, 2018
    Co-Authors: Anabella Tudora, Franzjosef Hambsch, Viorel Tobosaru
    Abstract:

    A new triangular form of the residual temperature distribution P(T), entering the Prompt emission models in which the sequential emission is globally taken into account (e.g., the Los Alamos model of Madland and Nix with subsequent improvements and the Point-by-Point model), is proposed. A deterministic treatment of the successive emission of Prompt Neutrons, which is based on recursive equations of the residual temperatures, was developed. This modeling was validated by the good description of many and different experimental data of Prompt emission (e.g., $\overline{\nu}(A)$ , $\langle\nu\rangle$ (TKE), $\langle\varepsilon\rangle (A)$ , $\langle\varepsilon\rangle$ (TKE), $\overline{E}_{\gamma} (A)$ , etc.) and the good agreement with the results of other Prompt emission models. To see a possible systematic behaviour of P(T) as a function of energy and fissioning nucleus, the deterministic treatment of sequential emission was applied to 11 nuclei undergoing fission (spontaneously or induced by thermal and fast Neutrons with energies up to the threshold of the second chance fission) for which reliable experimental fission fragment distributions Y(A, TKE) exist. The shapes of all P(T) distributions for the light and heavy fragment groups and for all fragments resulting from this modeling can be approximated with a triangular form. To make possible the use of this form into the Prompt emission models with a global treatment of sequential emission, a connection between the average residual temperature $\langle \mathrm{Tr} \rangle$ and the temperature of initial fragments $\langle \mathrm{Ti} \rangle$ is needed. An important finding of this study concerns the ratio $\langle \mathrm{Tr} \rangle / \langle \mathrm{Ti} \rangle$ , which is $ \approx 0.6$ for all studied fissioning systems. This result allows to obtain a new triangular form of P(T) defined only as a function of initial temperature, which is applicable to any fissioning system at any energy, in the frame of Prompt emission models with a global treatment of sequential emission.

  • point by point model description of experimental average Prompt Neutron multiplicity as a function of total kinetic energy of fission fragments
    Annals of Nuclear Energy, 2013
    Co-Authors: Anabella Tudora
    Abstract:

    Abstract The present Point by Point (PbP) model calculations of average Prompt Neutron multiplicity as a function of total kinetic energy 〈 ν 〉(TKE), performed for three fissioning systems 252 Cf(SF), 239 Pu( n th , f ) and 235 U( n th , f ), describe very well the experimental data over the entire TKE range, including not only the slope d TKE/ dν but also the flattening of experimental 〈 ν 〉 data at low TKE values. Present deterministic PbP model results of 〈 ν 〉(TKE) are analyzed comparatively with previous PbP 〈 ν 〉(TKE) results based on the same multi-parametric matrix ν ( Z , A , TKE) and different manners of averaging this matrix over the fission fragment distributions, as well as with previous and recent results of probabilistic Monte Carlo treatments. The average model parameters as a function of TKE provided by the PbP treatment exhibit nice and regular behaviours and can be fitted well. The resulted model parameter dependences on TKE allow the use of the most probable fragmentation approach (Los Alamos model with subsequent improvements) having the advantages to provide results at many TKE values in a very short calculation time (compared to the PbP model and Monte Carlo treatments) and also outside the TKE range where the PbP model is applicable. Possible explanations of discrepancies between the slopes of different sets of experimental 〈 ν 〉(TKE) data are mentioned, too.

  • 234u n f model description of sub barrier fission cross section resonances and calculation of Prompt Neutron emission data
    Physics Procedia, 2013
    Co-Authors: Anabella Tudora, F J Hambsch, Stephan Oberstedt
    Abstract:

    Abstract Neutron induced cross-sections of 234 U are calculated, focusing on the description of sub-barrier resonances in the fission cross-section. The correlation between the resonant behaviour of fission cross-section of fertile actinides (characterizing the pre-scission stage) and the visible fluctuations of their fission fragment and Prompt Neutron data (characterizing the post-scission stage), already discussed for the case of 238 U(n,f), is outlined and quantitatively supported in this case, too. The recently measured fission fragment distributions of 234 U(n,f) at incident energies covering the range 0.2-5 MeV, allow the averaging of multi-parametric matrices provided by the Point-by-Point (PbP) model, leading to interesting behaviours of Prompt Neutron data. For the first time the average Prompt Neutron multiplicity as a function of TKE is calculated at many incident energies (En) revealing interesting facts: the slope dTKE/dν does not vary with En and the flattening of at low TKE values is more pronounced at low En. Average model parameters (like energy release, Neutron separation energy from fragments, level density of fragments) as a function of TKE exhibit nice and regular behaviours that can be fitted very well. The obtained average parameter dependences on TKE allow the use of the most probable fragmentation approach (Los Alamos model with subsequent improvements) having as advantages a very short computing time compared to the PbP and Monte Carlo treatments and the possibility to extend the lower and upper limits of the TKE range.

  • point by point model calculation of the Prompt Neutron multiplicity distribution p ν for spontaneous and Neutron induced fission of actinides
    Annals of Nuclear Energy, 2010
    Co-Authors: Anabella Tudora, F J Hambsch
    Abstract:

    Abstract The Prompt Neutron multiplicity distribution P(ν) is a very sensitive quantity which depends on the model calculation of the multi-parametric matrix ν(A,TKE) and on the fission fragment distributions. The Point by Point model is able to give an excellent description of the existing P(ν) experimental data, this fact being exemplified in the present work for the following seven fissioning systems: 235U(nth,f), 239Pu(nth,f), 252Cf(SF), 248,244Cm(SF), 240,242Pu(SF). Taking into account the high sensitivity of P(ν) to the accuracy of the model used to calculate the matrix ν(A,TKE), the good agreement of the Point by Point model results with the experimental P(ν) data can be considered as a very important validation test for the Point by Point model itself and for the models and methods used to obtain the Point by Point model parameters.

Stephan Oberstedt - One of the best experts on this subject based on the ideXlab platform.

  • Prompt Neutron emission and energy balance in 235u n f
    European Physical Journal Web of Conferences, 2017
    Co-Authors: Alf Gook, Franzjosef Hambsch, Stephan Oberstedt
    Abstract:

    Investigations of Prompt fission Neutron (PFN) emission are of importance in understanding the fission process in general and the sharing of excitation energy among the fission fragments in particular. Experimental activities at JRC-Geel on PFN emission in response to OECD/NEA nuclear data requests is presented in this contribution. The focus lies on on-going investigations of PFN emission from the reaction 235 U(n,f) in the region of the resolved resonances taking place at the GELINA facility. For this reaction strong fluctuations of fission fragment mass distributions and mean total kinetic energy have been observed as a function of incident Neutron energy in the resonance region. In addition, fluctuations of Prompt Neutron multiplicities have also been observed. The goal of the present study is to verify the current knowledge of PFN multiplicity fluctuations and to study correlations with fission fragment properties. The experiment employs a scintillation detector array for Neutron detection, while fission fragment properties are determined via the double kinetic energy technique using a position sensitive twin ionization chamber. Results on PFN multiplicity correlations with fission fragment properties from the present study show significant differences compared to earlier studies on this reaction, induced by thermal Neutrons. Specifically, the total kinetic energy dependence of the Neutron multiplicity per fission shows an inverse slope FX 1TKE/FX 2ν approximately 35% weaker than observed in earlier studies of thermal Neutron induced fission on 235 U. The inverse slope is related to the energy carried away per emitted Neutron and is, thereby, closely connected to the energy balance of the fission reaction. The present result should have strong impact on the modeling of both Prompt Neutron and Prompt γ-ray emission in fission of the 236 U compound nucleus.

  • a position sensitive twin ionization chamber for fission fragment and Prompt Neutron correlation experiments
    Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2016
    Co-Authors: A Gook, Stephan Oberstedt, F J Hambsch, M Vidali, W Geerts, Sh Zeynalov
    Abstract:

    Abstract A twin position-sensitive Frisch grid ionization chamber, intended as a fission fragment detector in experiments to study Prompt fission Neutron correlations with fission fragment properties, is presented. Fission fragment mass and energies are determined by means of the double kinetic energy technique, based on conservation of mass and linear momentum. The position sensitivity is achieved by replacing each anode plate in the standard twin ionization chamber by a wire plane and a strip anode, both readout by means of resistive charge division. This provides information about the fission axis orientation, which is necessary to reconstruct the Neutron emission process in the fully accelerated fragment rest-frame. The energy resolution compared to the standard twin ionization chamber is found not to be affected by the modification. The angular resolution of the detector relative to an arbitrarily oriented axis is better than 7° FWHM. Results on Prompt fission Neutron angular distributions in 235 U(n,f) obtained with the detector in combination with an array of Neutron scintillation detectors is presented as a proof of principle.

  • 234u n f model description of sub barrier fission cross section resonances and calculation of Prompt Neutron emission data
    Physics Procedia, 2013
    Co-Authors: Anabella Tudora, F J Hambsch, Stephan Oberstedt
    Abstract:

    Abstract Neutron induced cross-sections of 234 U are calculated, focusing on the description of sub-barrier resonances in the fission cross-section. The correlation between the resonant behaviour of fission cross-section of fertile actinides (characterizing the pre-scission stage) and the visible fluctuations of their fission fragment and Prompt Neutron data (characterizing the post-scission stage), already discussed for the case of 238 U(n,f), is outlined and quantitatively supported in this case, too. The recently measured fission fragment distributions of 234 U(n,f) at incident energies covering the range 0.2-5 MeV, allow the averaging of multi-parametric matrices provided by the Point-by-Point (PbP) model, leading to interesting behaviours of Prompt Neutron data. For the first time the average Prompt Neutron multiplicity as a function of TKE is calculated at many incident energies (En) revealing interesting facts: the slope dTKE/dν does not vary with En and the flattening of at low TKE values is more pronounced at low En. Average model parameters (like energy release, Neutron separation energy from fragments, level density of fragments) as a function of TKE exhibit nice and regular behaviours that can be fitted very well. The obtained average parameter dependences on TKE allow the use of the most probable fragmentation approach (Los Alamos model with subsequent improvements) having as advantages a very short computing time compared to the PbP and Monte Carlo treatments and the possibility to extend the lower and upper limits of the TKE range.

  • sub barrier resonance fission and its effects on fission fragment properties exemplified on 234 238u n f
    EPJ Web of Conferences, 2013
    Co-Authors: A Tudora, F J Hambsch, Stephan Oberstedt
    Abstract:

    The correlation between the sub-barrier resonant behaviour of fission cross- section of non-fissile actinides (pre-scission stage) and the visible fluctuations of their fission fragment and Prompt Neutron data (post-scission stage) around the incident energies of sub-barrier resonances is outlined and supported by quantitative results for two fissioning systems 234,238 U(n,f). These quantitative results refer to both stages of the fission process: a) The pre-scission stage including the calculation of Neutron induced cross-sections with focus on fission. Calculations are done in the frame of the refined statistical model for fission with sub-barrier effects also extended to take into account the multi-modal fission. b) The post-scission stage including the Prompt Neutron emission treated in the frame of the Point-by-Point model. Total quantities characterizing the fission fragments and the Prompt Neutrons obtained by averaging the Point-by-Point results as a function of fragment over the fission fragment distributions reveal variations around the energies of sub-barrier resonances in the fission cross- section.

  • impact of Prompt Neutron corrections on final fission fragment distributions
    Physical Review C, 2012
    Co-Authors: Franzjosef Hambsch, Ali Aladili, Stephan Pomp, Stephan Oberstedt
    Abstract:

    Background: One important quantity in nuclear fission is the average number of Prompt Neutrons emitted from the fission fragments, the Prompt Neutron multiplicity, $\overline{\ensuremath{\nu}}$. The total number of Prompt fission Neutrons, ${\overline{\ensuremath{\nu}}}_{\text{tot}}$, increases with increasing incident Neutron energy. The Prompt-Neutron multiplicity is also a function of the fragment mass and the total kinetic energy of the fragmentation. Those data are only known in sufficient detail for a few thermal-Neutron-induced fission reactions on, for example, ${}^{233,235}$U and ${}^{239}$Pu. The enthralling question has always been asked how the additional excitation energy is shared between the fission fragments. The answer to this question is important in the analysis of fission-fragment data taken with the double-energy technique. Although in the traditional approach the excess Neutrons are distributed equally across the mass distribution, a few experiments showed that those Neutrons are predominantly emitted by the heavy fragments.Purpose: We investigated the consequences of the $\ensuremath{\nu}(A,\mathrm{TKE},{E}_{\mathrm{n}})$ distribution on the fission fragment observables.Methods: Experimental data obtained for the ${}^{234}$U($n,\phantom{\rule{-0.16em}{0ex}}f$) reaction with a Twin Frisch Grid Ionization Chamber, were analyzed assuming two different methods for the Neutron evaporation correction. The effect of the two different methods on the resulting fragment mass and energy distributions is studied.Results: We found that the preNeutron mass distributions obtained via the double-energy technique become slightly more symmetric, and that the impact is larger for postNeutron fission-fragment distributions. In the most severe cases, a relative yield change up to 20--30$%$ was observed.Conclusions: We conclude that the choice of the Prompt-Neutron correction method has strong implications on the understanding and modeling of the fission process and encourages new experiments to measure fission fragments in coincidence with Prompt fission Neutrons. Even more, the correct determination of postNeutron fragment yields has an impact on the reliable assessment of the nuclear waste inventory, as well as on the correct prediction of delayed Neutron precursor yields.

Kengo Hashimoto - One of the best experts on this subject based on the ideXlab platform.

  • experimental study on Neutron correlation analysis for a subcritical system driven by a pulsed spallation Neutron source in kuca
    Epj Web of Conferences, 2021
    Co-Authors: Kunihiro Nakajima, Masao Yamanaka, Cheol Ho Pyeon, Kazuki Takahashi, Atsushi Sakon, Sinya Hohara, Tadafumi Sano, Kengo Hashimoto
    Abstract:

    The Feynman-α and the Rossi-α methods have been frequently employed to determine the subcriticality of subcritical reactor systems driven by Poisson source such as Am-Be Neutron source. In actual accelerator-driven systems (ADS), a spallation device will be applied as an intense Neutron source. This device will be probably operated in a pulse mode and it is impossible to apply a conventional analysis method to determine the subcriticality in any ADS. In previous theoretical studies, some advanced formulae of Neutron correlation analysis for spallation Neutron source have been presented. However, the experimental study has been hardly reported to date. The major objectives of this study are to examine experimentally an applicability of these complicated formulae to a subcritical reactor system driven by an actual pulsed spallation Neutron source and to determine the Prompt-Neutron decay constant α of the system. To achieve these goals, we constructed an ADS core at the Kyoto University Critical Assembly (KUCA). The core was composed of highly-enriched uranium fuel assemblies surrounded by many polyethylene reflector assemblies. We carried out a series of the Feynman-α and the Rossi-α analyses for the system driven by pulsed spallation source. As a result, the Prompt-Neutron decay constants were experimentally obtained by using a fitting formula. The Prompt-Neutron decay constants determined by Feynman-α and Rossi-α analyses agrees with each other within a statistical error range of least-squares fitting.

  • determination of Prompt Neutron decay constant from phase shift between beam current and Neutron detection signals for an accelerator driven system in the kyoto university critical assembly
    Journal of Nuclear Science and Technology, 2015
    Co-Authors: Atsushi Sakon, Cheol Ho Pyeon, Kengo Hashimoto, Sinya Hohara, Tadafumi Sano, Wataru Sugiyama, Takahiro Yagi, Takaaki Ohsawa
    Abstract:

    A unique power spectral analysis for a subcritical reactor system driven by a pulsed 14 MeV Neutron source was carried out at the Kyoto University Critical Assembly (KUCA). In this analysis, a complex cross-power spectral density between time-sequence signal data from an accelerator beam ammeter and a Neutron detector was measured to determine the Prompt-Neutron decay constant of an accelerator-driven system (ADS) from the phase data of the spectral density. Assuming the one-point kinetics model, in theory, the decay constant can be arithmetically derived from the phase at the integral multiples of the pulse repetition frequency. However, the actual derivation from the phase at a pulse repetition frequency of 20 Hz considerably underestimated the Prompt-Neutron decay constant, compared with that obtained by a previous pulsed Neutron experiment, and the derived decay constant apparently decreased with an increase in the multiple of the pulsed repetition frequency. Considering a lag time in detector respons...

  • power spectral analysis for a thermal subcritical reactor system driven by a pulsed 14 mev Neutron source
    Journal of Nuclear Science and Technology, 2013
    Co-Authors: Atsushi Sakon, Cheol Ho Pyeon, Tsuyoshi Misawa, Kengo Hashimoto, Tadafumi Sano, Wataru Sugiyama, Hiroshi Taninaka, Hironobu Unesaki, Takaaki Ohsawa
    Abstract:

    A series of power spectral analyses for a thermal subcritical reactor system driven by a pulsed 14 MeV Neutron source was carried out at Kyoto University Critical Assembly (KUCA), to determine the Prompt-Neutron decay constant of the accelerator-driven system (ADS). The cross-power spectral density between time-sequence signal data of two Neutron detectors was composed of a familiar continuous reactor noise component and many delta-function-like peaks at the integral multiple of pulse repetition frequency. The Prompt-Neutron decay constant inferred from the reactor noise component of the cross-power spectral density was consistent with that obtained by a pulsed Neutron experiment. However, the reactor noise component of the auto-power spectral density of each detector was hidden by a white chamber noise in the higher-frequency range and this feature resulted in a considerable underestimation of the decay constant. For several runs with a low pulse-repetition frequency, furthermore, we attempted to infer t...

  • feynman α analysis for a thermal subcritical reactor system driven by an unstable 14mev Neutron source
    Journal of Nuclear Science and Technology, 2011
    Co-Authors: Hiroshi Taninaka, Cheol Ho Pyeon, Tsuyoshi Misawa, Kengo Hashimoto, Tadafumi Sano, Wataru Sugiyama, Atsuko Miyoshi, Takaaki Ohsawa
    Abstract:

    In a series of Feynman-α correlation measurements for a thermal Accelerator-Driven System (ADS) with 14MeV Neutrons at the Kyoto University Critical Assembly (KUCA), an unstable accelerator condition such as a drift of beam current has been frequently observed. Neutron source instability caused by such unavoidable beam-current instability resulted in a divergent variance-to-mean ratio and, consequently, the correlation analysis failed. Nevertheless, we attempted to apply a difference-filtering technique to the correlation analysis to reduce the influence of the above instability. The present attempt resulted in consistent Prompt-Neutron decay constants with those obtained in a previous pulsed Neutron experiment. The application of the filtering is expected to enhance the robustness of Feynman-α analysis against various instabilities of accelerator operation in actual ADS.

  • determination of lambda mode eigenvalue separation of a thermal accelerator driven system from pulsed Neutron experiment
    Journal of Nuclear Science and Technology, 2010
    Co-Authors: Hiroshi Taninaka, Cheol Ho Pyeon, Tsuyoshi Misawa, Kengo Hashimoto, Tadafumi Sano, Takaaki Ohsawa
    Abstract:

    Basic research on the Accelerator-Driven System (ADS) with thermal Neutron spectrum has been promoted by the Kyoto University Research Reactor Institute. At the Kyoto University Critical Assembly (KUCA), various experiments on thermal ADS with a pulsed spallation source are planned. In such an ADS, Neutron flux distribution may be sensitive to the injection of Neutrons, and the high sensitivity results in various spatial effects. In this study, a pulsed Neutron experiment with 14MeV Neutrons was carried out in a thermal ADS of KUCA, to determine the λ-mode eigenvalue separation, which is a quantitative indication of spatial effects. An original data-processing technique was applied to infer Prompt-Neutron decay constants of fundamental and higher modes from Neutron count decay data, and then the eigenvalue separation around 13%Δk/k was obtained from these decay constants.

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