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Stephan Oberstedt - One of the best experts on this subject based on the ideXlab platform.
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Neutron Multiplicity Correlations with Fission Fragment Mass and Energy from
'EDP Sciences', 2020Co-Authors: Alf Gook, Franzjosef Hambsch, Stephan OberstedtAbstract:There exists experimental evidence for strong fluctuations of the average neutron multiplicity from resonance to resonance in 239Pu(n,f). These fluctuations have been shown to impact nuclear reactor benchmarks by reducing the criticality. The fluctuating neutron multiplicity can be explained as a consequence of the competition between direct Fission and the (n,γf) process. However, there is also evidence for fluctuations of the Fission Fragment mass yields from resonance to resonance. The mass yield fluctuations may also contribute to fluctuations of the neutron multiplicity averaged over all Fission Fragment masses. In order to model the contribution to the neutron multiplicity fluctuations by the Fission Fragment mass yield fluctuations new data on the correlations between Fission Fragment properties and neutron multiplicities are in need. We present experiments carried out to determine prompt neutron multiplicity correlations with Fission Fragment masses and total kinetic energies in the reaction 239Pu(n,f). The experiment has been performed at the GELINA facility at JRC-Geel. A twin position-sensitive Frisch-grid ionization chamber is used for Fission Fragment identification via the double kinetic energy technique. An array of scintillation detectors is employed for neutron counting. Correlations between average neutron multiplicities and Fission Fragment properties have been measured with improved resolution in both mass and TKE, compared to data from the literature
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prompt neutron emission and energy balance in 235u n f
European Physical Journal Web of Conferences, 2017Co-Authors: Alf Gook, Franzjosef Hambsch, Stephan OberstedtAbstract: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.
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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, 2016Co-Authors: Alf Gook, Stephan Oberstedt, F J Hambsch, M Vidali, W Geerts, Sh. ZeynalovAbstract: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.
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sub barrier resonance Fission and its effects on Fission Fragment properties exemplified on 234 238u n f
EPJ Web of Conferences, 2013Co-Authors: Anabella Tudora, F J Hambsch, Stephan OberstedtAbstract: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.
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impact of prompt neutron corrections on final Fission Fragment distributions
Physical Review C, 2012Co-Authors: Franzjosef Hambsch, Ali Aladili, Stephan Pomp, Stephan OberstedtAbstract: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.
Peter Moller - One of the best experts on this subject based on the ideXlab platform.
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correlation studies of Fission Fragment neutron multiplicities
arXiv: Nuclear Theory, 2020Co-Authors: M Albertsson, Jorgen Randrup, Peter Moller, Bg Carlsson, T Dossing, Sven ÅbergAbstract:We calculate neutron multiplicities from Fission Fragments with specified mass numbers for events having a specified total Fragment kinetic energy. The shape evolution from the initial compound nucleus to the scission configurations is obtained with the Metropolis walk method on the five-dimensional potential-energy landscape, calculated with the macroscopic-microscopic method for the three-quadratic-surface shape family. Shape-dependent microscopic level densities are used to guide the random walk, to partition the intrinsic excitation energy between the two proto-Fragments at scission, and to determine the spectrum of the neutrons evaporated from the Fragments. The contributions to the total excitation energy of the resulting Fragments from statistical excitation and shape distortion at scission is studied. Good agreement is obtained with available experimental data on neutron multiplicities in correlation with Fission Fragments from $^{235}$U(n$_{\rm th}$,f). At higher neutron energies a superlong Fission mode appears which affects the dependence of the observables on the total Fragment kinetic energy.
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Calculated Fission-Fragment mass yields and average total kinetic energies of heavy and superheavy nuclei
'Springer Science and Business Media LLC', 2020Co-Authors: Martin Albertsson, Jorgen Randrup, Peter Moller, Gillis B. Carlsson, Thomas Døssing, Sven ÅbergAbstract:Fission-Fragment mass and total-kinetic-energy (TKE) distributions following Fission of even-even nuclides in the region $$74 \le Z \le 126$$ and $$92 \le N \le 230$$, comprising 896 nuclides have been calculated using the Brownian shape-motion method. The emphasis is the region of superheavy nuclei. To show compatibility with earlier results the calculations are extended to include earlier studied regions. An island of asymmetric Fission is obtained in the superheavy region, $$106\le Z\le 114$$ and $$162\le N\le 176$$, where the heavy Fragment is found to be close to $$^{208}$$Pb and the light Fragment adjusts accordingly. Most experimentally observed $$\alpha $$-decay chains of superheavy nuclei with $$Z > 113 $$ terminate by spontaneous Fission in our predicted region of asymmetric Fission. In these cases, the pronounced large asymmetry is accompanied by a low TKE value compatible with measurements
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a method to calculate Fission Fragment yields y z n versus proton and neutron number in the brownian shape motion model application to calculations of u and pu charge yields
arXiv: Nuclear Theory, 2015Co-Authors: Peter Moller, Takatoshi IchikawaAbstract:We propose a method to calculate the two-dimensional (2D) Fission-Fragment yield $Y(Z,N)$ versus both proton and neutron number, with inclusion of odd-even staggering effects in both variables. The approach is to use Brownian shape-motion on a macroscopic-microscopic potential-energy surface which, for a particular compound system is calculated versus four shape variables: elongation (quadrupole moment $Q_2$), neck $d$, left nascent Fragment spheroidal deformation $\epsilon_{\rm f1}$, right nascent Fragment deformation $\epsilon_{\rm f2}$ and two asymmetry variables, namely proton and neutron numbers in each of the two Fragments. The extension of previous models 1) introduces a method to calculate this generalized potential-energy function and 2) allows the correlated transfer of nucleon pairs in one step, in addition to sequential transfer. In the previous version the potential energy was calculated as a function of $Z$ and $N$ of the compound system and its shape, including the asymmetry of the shape. We outline here how to generalize the model from the "compound-system" model to a model where the emerging Fragment proton and neutron numbers also enter, over and above the compound system composition.
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brownian shape motion on five dimensional potential energy surfaces nuclear Fission Fragment mass distributions
Physical Review Letters, 2011Co-Authors: Jorgen Randrup, Peter MollerAbstract:: Although nuclear Fission can be understood qualitatively as an evolution of the nuclear shape, a quantitative description has proven to be very elusive. In particular, until now, there existed no model with demonstrated predictive power for the Fission-Fragment mass yields. Exploiting the expected strongly damped character of nuclear dynamics, we treat the nuclear shape evolution in analogy with Brownian motion and perform random walks on five-dimensional Fission potential-energy surfaces which were calculated previously and are the most comprehensive available. Test applications give good reproduction of highly variable experimental mass yields. This novel general approach requires only a single new global parameter, namely, the critical neck size at which the mass split is frozen in, and the results are remarkably insensitive to its specific value.
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brownian shape motion on five dimensional potential energy surfaces nuclear Fission Fragment mass distributions
Physical Review Letters, 2011Co-Authors: Jorgen Randrup, Peter MollerAbstract:Although nuclear Fission can be understood qualitatively as an evolution of the nuclear shape, a quantitative description has proven to be very elusive. In particular, until now, there existed no model with demonstrated predictive power for the Fission-Fragment mass yields. Exploiting the expected strongly damped character of nuclear dynamics, we treat the nuclear shape evolution in analogy with Brownian motion and perform random walks on five-dimensional Fission potential-energy surfaces which were calculated previously and are the most comprehensive available. Test applications give good reproduction of highly variable experimental mass yields. This novel general approach requires only a single new global parameter, namely, the critical neck size at which the mass split is frozen in, and the results are remarkably insensitive to its specific value.
Jorgen Randrup - One of the best experts on this subject based on the ideXlab platform.
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correlation studies of Fission Fragment neutron multiplicities
arXiv: Nuclear Theory, 2020Co-Authors: M Albertsson, Jorgen Randrup, Peter Moller, Bg Carlsson, T Dossing, Sven ÅbergAbstract:We calculate neutron multiplicities from Fission Fragments with specified mass numbers for events having a specified total Fragment kinetic energy. The shape evolution from the initial compound nucleus to the scission configurations is obtained with the Metropolis walk method on the five-dimensional potential-energy landscape, calculated with the macroscopic-microscopic method for the three-quadratic-surface shape family. Shape-dependent microscopic level densities are used to guide the random walk, to partition the intrinsic excitation energy between the two proto-Fragments at scission, and to determine the spectrum of the neutrons evaporated from the Fragments. The contributions to the total excitation energy of the resulting Fragments from statistical excitation and shape distortion at scission is studied. Good agreement is obtained with available experimental data on neutron multiplicities in correlation with Fission Fragments from $^{235}$U(n$_{\rm th}$,f). At higher neutron energies a superlong Fission mode appears which affects the dependence of the observables on the total Fragment kinetic energy.
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Calculated Fission-Fragment mass yields and average total kinetic energies of heavy and superheavy nuclei
'Springer Science and Business Media LLC', 2020Co-Authors: Martin Albertsson, Jorgen Randrup, Peter Moller, Gillis B. Carlsson, Thomas Døssing, Sven ÅbergAbstract:Fission-Fragment mass and total-kinetic-energy (TKE) distributions following Fission of even-even nuclides in the region $$74 \le Z \le 126$$ and $$92 \le N \le 230$$, comprising 896 nuclides have been calculated using the Brownian shape-motion method. The emphasis is the region of superheavy nuclei. To show compatibility with earlier results the calculations are extended to include earlier studied regions. An island of asymmetric Fission is obtained in the superheavy region, $$106\le Z\le 114$$ and $$162\le N\le 176$$, where the heavy Fragment is found to be close to $$^{208}$$Pb and the light Fragment adjusts accordingly. Most experimentally observed $$\alpha $$-decay chains of superheavy nuclei with $$Z > 113 $$ terminate by spontaneous Fission in our predicted region of asymmetric Fission. In these cases, the pronounced large asymmetry is accompanied by a low TKE value compatible with measurements
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brownian shape motion on five dimensional potential energy surfaces nuclear Fission Fragment mass distributions
Physical Review Letters, 2011Co-Authors: Jorgen Randrup, Peter MollerAbstract:: Although nuclear Fission can be understood qualitatively as an evolution of the nuclear shape, a quantitative description has proven to be very elusive. In particular, until now, there existed no model with demonstrated predictive power for the Fission-Fragment mass yields. Exploiting the expected strongly damped character of nuclear dynamics, we treat the nuclear shape evolution in analogy with Brownian motion and perform random walks on five-dimensional Fission potential-energy surfaces which were calculated previously and are the most comprehensive available. Test applications give good reproduction of highly variable experimental mass yields. This novel general approach requires only a single new global parameter, namely, the critical neck size at which the mass split is frozen in, and the results are remarkably insensitive to its specific value.
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brownian shape motion on five dimensional potential energy surfaces nuclear Fission Fragment mass distributions
Physical Review Letters, 2011Co-Authors: Jorgen Randrup, Peter MollerAbstract:Although nuclear Fission can be understood qualitatively as an evolution of the nuclear shape, a quantitative description has proven to be very elusive. In particular, until now, there existed no model with demonstrated predictive power for the Fission-Fragment mass yields. Exploiting the expected strongly damped character of nuclear dynamics, we treat the nuclear shape evolution in analogy with Brownian motion and perform random walks on five-dimensional Fission potential-energy surfaces which were calculated previously and are the most comprehensive available. Test applications give good reproduction of highly variable experimental mass yields. This novel general approach requires only a single new global parameter, namely, the critical neck size at which the mass split is frozen in, and the results are remarkably insensitive to its specific value.
Franzjosef Hambsch - One of the best experts on this subject based on the ideXlab platform.
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Neutron Multiplicity Correlations with Fission Fragment Mass and Energy from
'EDP Sciences', 2020Co-Authors: Alf Gook, Franzjosef Hambsch, Stephan OberstedtAbstract:There exists experimental evidence for strong fluctuations of the average neutron multiplicity from resonance to resonance in 239Pu(n,f). These fluctuations have been shown to impact nuclear reactor benchmarks by reducing the criticality. The fluctuating neutron multiplicity can be explained as a consequence of the competition between direct Fission and the (n,γf) process. However, there is also evidence for fluctuations of the Fission Fragment mass yields from resonance to resonance. The mass yield fluctuations may also contribute to fluctuations of the neutron multiplicity averaged over all Fission Fragment masses. In order to model the contribution to the neutron multiplicity fluctuations by the Fission Fragment mass yield fluctuations new data on the correlations between Fission Fragment properties and neutron multiplicities are in need. We present experiments carried out to determine prompt neutron multiplicity correlations with Fission Fragment masses and total kinetic energies in the reaction 239Pu(n,f). The experiment has been performed at the GELINA facility at JRC-Geel. A twin position-sensitive Frisch-grid ionization chamber is used for Fission Fragment identification via the double kinetic energy technique. An array of scintillation detectors is employed for neutron counting. Correlations between average neutron multiplicities and Fission Fragment properties have been measured with improved resolution in both mass and TKE, compared to data from the literature
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prompt neutron emission and energy balance in 235u n f
European Physical Journal Web of Conferences, 2017Co-Authors: Alf Gook, Franzjosef Hambsch, Stephan OberstedtAbstract: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.
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prompt neutron multiplicity in correlation with Fragments from spontaneous Fission of cf 252
Physical Review C, 2014Co-Authors: Alf Gook, Franzjosef Hambsch, M VidaliAbstract:The spontaneous Fission of $^{252}\mathrm{Cf}$ serves as an excellent benchmark of prompt emission in Fission since experimental data can be obtained without the need of an incident beam. With the purpose of providing experimental data on the prompt Fission neutron properties in correlation with Fission-Fragment characteristics, an experiment on $^{252}\mathrm{Cf}$(SF) has been performed. In addition, the experiment serves as a benchmark of setup and analysis procedures for measurements of fluctuations in the prompt-neutron properties as a function of incident neutron energy in Fission of the major actinides $^{235}\mathrm{U}$ and $^{239}\mathrm{Pu}$. The experiment employs a twin Frisch grid ionization chamber as Fission-Fragment detector while neutrons were counted by using a liquid scintillator placed along the symmetry axis of the ionization chamber. Average neutron multiplicity has been obtained as a function of Fission-Fragment mass and total kinetic energy (TKE). The average multiplicity as a function of mass agrees well with available data in the literature in the mass range from 80 to 170 u. The existence of additional sawtooth structures in the far asymmetric mass region could not be confirmed, although the statistical accuracy of the present experiment is as good as the previous study where such structures have been reported [Nucl. Phys. A 490, 307 (1988).]. The available data in the literature on the TKE dependence of the multiplicity show strong deviations. Therefore, effort was focused on investigating experimental factors in low-efficiency neutron-counting experiments that may lead to faulty determination of this dependence. Taking these factors into account, a result that agrees well with data from high-efficiency neutron-counting experiments is obtained. The experimental arrangement allows determination of the angle between the detected neutron and the Fission axis, which permits the neutron properties to be transformed into the Fission-Fragment rest frame. Fission neutron emission spectra in the Fragment center-of-mass frame have thereby been obtained as a function of the Fission-Fragment mass and TKE.
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impact of prompt neutron corrections on final Fission Fragment distributions
Physical Review C, 2012Co-Authors: Franzjosef Hambsch, Ali Aladili, Stephan Pomp, Stephan OberstedtAbstract: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.
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dsp algorithms for Fission Fragment and prompt Fission neutron spectroscopy
1ST INTERNATIONAL CONFERENCE ON APPLICATIONS OF MATHEMATICS IN TECHNICAL AND NATURAL SCIENCES, 2009Co-Authors: O. V. Zeynalova, Franzjosef Hambsch, Stephan Oberstedt, Sh. Zeynalov, I FabryAbstract:Digital signal processing (DSP) algorithms are in high demand for modern nuclear Fission investigation due to importance of increase the accuracy of fissile nuclear data for new generation of nuclear power stations. DSP algorithms for Fission Fragment (FF) and prompt Fission neutron (PFN) spectroscopy are described in the present work. The twin Frisch‐grid ionization chamber (GTIC) is used to measure the kinetic energy‐, mass‐ and angular distributions of the FF in the 252Cf(SF) reaction. Along with the neutron time‐of‐flight (TOF) measurement the correlation between neutron emission and FF mass and energy is investigated. The TOF is measured between common cathode of the GTIC and the neutron detector (ND) pulses. Waveform digitizers (WFD) having 12 bit amplitude resolution and 100 MHz sampling frequency are used for the detector pulse sampling. DSP algorithms are developed as recursive procedures to perform the signal processing, similar to those available in various nuclear electronics modules, such as constant fraction discriminator (CFD), pulse shape discriminator (PSD), peak‐sensitive analogue‐to‐digital converter (pADC) and pulse shaping amplifier (PSA). To measure the angle between FF and the cathode plane normal to the GTIC a new algorithm is developed having advantage over the traditional analogue pulse processing schemes. Algorithms are tested by comparing the numerical simulation of the data analysis of the 252Cf(SF) reaction with data available from literature.Digital signal processing (DSP) algorithms are in high demand for modern nuclear Fission investigation due to importance of increase the accuracy of fissile nuclear data for new generation of nuclear power stations. DSP algorithms for Fission Fragment (FF) and prompt Fission neutron (PFN) spectroscopy are described in the present work. The twin Frisch‐grid ionization chamber (GTIC) is used to measure the kinetic energy‐, mass‐ and angular distributions of the FF in the 252Cf(SF) reaction. Along with the neutron time‐of‐flight (TOF) measurement the correlation between neutron emission and FF mass and energy is investigated. The TOF is measured between common cathode of the GTIC and the neutron detector (ND) pulses. Waveform digitizers (WFD) having 12 bit amplitude resolution and 100 MHz sampling frequency are used for the detector pulse sampling. DSP algorithms are developed as recursive procedures to perform the signal processing, similar to those available in various nuclear electronics modules, such as ...
Satoshi Chiba - One of the best experts on this subject based on the ideXlab platform.
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prompt and delayed neutron emissions and Fission product yield calculations with hauser feshbach statistical decay theory and summation calculation method
European Physical Journal Web of Conferences, 2019Co-Authors: Shin Okumura, T Kawano, Satoshi ChibaAbstract:We demonstrate the neutron emission and Fission product yield calculations using the Hauser–Feshbach Fission Fragment Decay (HF3 D) model and β decay. The HF3 D model calculates the statistical decay of more than 500 primary Fission Fragment pairs formed by the neutron induced Fission of 235 U. In order to calculate the prompt neutron and photon emissions, the primary Fission Fragment distributions, i.e. mass, charge, excitation energy, spin and parity are deterministically generated and numerically integrated for all Fission Fragments. The calculated prompt neutron multiplicities, independent Fission product yield are fully consistent each other. We combine the β -decay and the summation calculations with the HF3 D model calculation to obtain the cumulative Fission product yield, decay heat and delayed neutron yield. The calculated Fission observables are compared with available experimental data.
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235u n f independent Fission product yield and isomeric ratio calculated with the statistical hauser feshbach theory
Journal of Nuclear Science and Technology, 2018Co-Authors: Shin Okumura, T Kawano, P Jaffke, P Talou, Satoshi ChibaAbstract:ABSTRACTWe have developed a Hauser–Feshbach Fission Fragment decay model, HF3D, which can be applied to the statistical decay of more than 500 primary Fission Fragment pairs (1,000 nuclides) produced by the neutron induced Fission of 235U. The HF3D model numerically integrates Fission Fragment yield and their initial excitation energy, spin and parity distributions for these 1,000 nuclides. The Fission Fragment yield Y(A) and the total kinetic energy are model inputs, and we estimate them from available experimental data for the 235U(nth,f) system. The model parameters in the statistical decay calculation are adjusted to reproduce some Fission observables, such as the neutron emission multiplicity vˉ, its distribution P(ν), and the mass dependence vˉ(A). The calculated Fission product yield (FPY) and isomeric ratio (IR) are compared with experimental data. The calculated independent FPY YI(A) at the thermal energy reproduces the experimental data well, while the calculated IRs tend to be lower than the Ma...
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the r process element abundance with a realistic Fission Fragment mass distribution
ORIGIN OF MATTER AND EVOLUTION OF GALAXIES: The 10th International Symposium on#N#Origin of Matter and Evolution of Galaxies: From the Dawn of Univers, 2008Co-Authors: Satoshi Chiba, S Tatsuda, Takahiro Wada, M Ohta, Kohsuke Sumiyoshi, Kaori Otsuki, Hiroyuki Koura, Toshiki Maruyama, Takahiro Tachibana, Toshitaka KajinoAbstract:Effect of the β‐delayed Fission in r‐process abundance is investigated with a realistic model for the Fission Fragment mass distribution (FFMD). The data base for the FFMD is constructed based on the two‐center shell model and multi‐dimensional Langevin calculation. The β‐decay rates including neutron emission and β‐delayed Fission are also newly calculated with 2nd version of the the gross theory. The differences appeared in the final element abundance calculated with and without Fission process, with different β‐delayed Fission rates are demonstrated.
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Fission Fragment mass distribution for nuclei in the r process region
TOURS SYMPOSIUM ON NUCLEAR PHYSICS VI, 2007Co-Authors: S Tatsuda, Satoshi Chiba, K Hashizume, Takahiro Wada, M Ohta, Kohsuke Sumiyoshi, Kaori Otsuki, Toshitaka Kajino, Hiroyuki Koura, Y AritomoAbstract:The Fission Fragment mass distribution is estimated theoretically on about 2000 nuclides which might have a critical role on the r‐process nucleosynthesis through Fission (Z>85). The mass distribution of Fission Fragment is derived by considering the location and the depth of valleys of potential energy surface near scission point of nuclei calculated by means of the liquid drop model with the shell energy correction by the Two‐Center shell model. The guiding principle of determining the Fission mass asymmetry is the behavior of the Fission paths from the saddle to the scission point given by the Langevin calculation.