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Academic literature on the topic 'Neutrons Prompts de Fission'

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Published: 25 May 2024

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Journal articles on the topic "Neutrons Prompts de Fission"

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Lovell, A. E., P. Talou, I. Stetcu, and K. J. Kelly. "Anisotropy in fission fragment and prompt neutron angular distributions." EPJ Web of Conferences 256 (2021): 00009. http://dx.doi.org/10.1051/epjconf/202125600009.

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Several physics mechanisms can lead to the deviation from an isotropic angular distribution for both fission fragments and the neutrons that are emitted during the fission event. Two of these effects have recently been implemented into CGMF, the Monte Carlo fission event generator developed at Los Alamos National Laboratory: angular distribution sampling for fission fragments and pre-equilibrium neutrons (those emitted before the compound nucleus forms). Using these new developments, we show that the anisotropy of the neutrons reflects the anisotropy of the fission fragments, in particular as the outgoing energy of neutrons increases. Correlations between the fission fragment and neutron anisotropies could be used to extract the fission fragment anisotropy from the neutron angular distributions.
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Oprea, Cristiana, Alexandru Mihul, and Alexandru Oprea. "Advanced Modelling of 238U(n,f) in a Fast Reactor Application." EPJ Web of Conferences 211 (2019): 04008. http://dx.doi.org/10.1051/epjconf/201921104008.

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Fast neutron reactors, as a possible future solution on energy demand of human society, based on fission process of 238U, request new and reliable nuclear data necessary for new generation reactors design. Fission process induced by fast neutrons on 238U was investigated. Fission observables like cross sections and their uncertainties, fission fragment mass distribution, prompt neutrons emission, isomer ratios and other parameters were obtained by using Talys computer code or programs realized by authors. Then the production of isotopes like 135,133Xe, 99Mo, 131I, 89Y as well as yields of fissile nuclei were evaluated. Obtained theoretical evaluations are compared with existing experimental data.
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Kelly, Keegan J., Matthew Devlin, Jaime A. Gomez, John M. O’Donnell, Terry N. Taddeucci, Robert C. Haight, Hye Young Lee, et al. "Measurements of the Prompt Fission Neutron Spectrum at LANSCE: The Chi-Nu Experiment." EPJ Web of Conferences 193 (2018): 03003. http://dx.doi.org/10.1051/epjconf/201819303003.

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The goal of the Chi-Nu experiment at the Los Alamos Neutron Science Center is to measure the prompt fission neutron spectra from major actinides using a double time-of-flight method with a pulsed, white incoming neutron source. Fission events are detected with a parallel-plate avalanche counter and outgoing neutrons are detected with either a 6Li-glass or liquid scintillator detector array for low- or high-energy neutrons, respectively. A detector response matrix for the interaction of neutrons with the experimental environment for neutrons measured with the Chi-Nu 6Li-glass detector array has been calculated to obtain a full understanding of the measured Chi-Nu data and also to allow for nearly instantaneous production of simulated Chi-Nu data spectra. Prompt fission neutron spectra corresponding to 19 incoming neutron energy ranges from 0.7-20 MeV have been extracted using the ratio-of-ratios method with Chi-Nu 6Li-glass data on the neutron-induced fission of 235U.
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Stanescu, Razvan, Hadrick Green, Toby Morris, Gencho Rusev, and Marian Jandel. "Prompt Fission Gamma-Ray Measurements at UML Research Reactor." EPJ Web of Conferences 242 (2020): 01009. http://dx.doi.org/10.1051/epjconf/202024201009.

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Neutron-induced fission of 235U was studied at the thermal column of the UMass Lowell 1 MW Research Reactor. A collimated, 2.25-inch diameter beam of thermal neutrons with the flux of ~5x105 n/cm2/sec induced fission reaction on a plate of low-enriched uranium with the areal density ~25 mg/cm2 of 235U. We have used the prompt fission-neutron tagging method to identify the fission reaction in the off-line analysis. The method employs the pulse-shape discrimination of neutrons and gamma-ray events in stilbene scintillator and enables identification of coincidence events of prompt fission gamma-rays and prompt fission neutrons in coincidence time intervals less than 20-30 ns. The prompt gamma-ray radiation was detected using two co-linear NaI(Tl) detectors. The measured spectra of prompt-fission gamma rays between 150 keV and 6 MeV are presented. The results from these initial measurements demonstrate the feasibility of the experimental method. Future measurements with extended arrays of detectors are planned.
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Devlin, Matthew, Jaime A. Gomez, Keegan J. Kelly, John M. O'Donnell, Robert C. Haight, Terry N. Taddeucci, Denise Neudecker, et al. "Prompt Fission Neutron Spectra for Neutron-Induced Fission of 239Pu and 235U." EPJ Web of Conferences 239 (2020): 01003. http://dx.doi.org/10.1051/epjconf/202023901003.

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We report the current results of a large effort to accurately measure the Prompt Fission Neutron Spectra (PFNS) for neutron-induced fission of 235U and 239Pu for incident neutrons with energies from 1 to 20 MeV. The Chi-Nu experiment at the Los Alamos Neutron Science Center used an unmoderated, white spectrum of neutrons to induce fission in actinide samples that were placed inside a parallel plate avalanche counter to provide a fast fission signal. A double time-of-flight technique was used to determine the incoming and outgoing neutron energies. Two neutron detector arrays, one with 54 liquid scintillators and another with 22 lithium glass detectors, were used to detect the outgoing neutrons and measure the PFNS distributions over a wide range in outgoing neutron energy, from below 100 keV to 10 MeV. Extensive Monte Carlo modeling was used to understand the experiment response and extract the PFNS. Systematic errors and uncertainties in the method have been examined and quantified. A summary of these results for incoming energies from 1 to 5 MeV is presented here.
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Vorobyev, Alexander, Oleg Shcherbakov, Alexei Gagarski, Gennadi’ski Val, and Tatiana’mina Kuz. "Experimental estimation of the “scission” neutron yield in the thermal neutron induced fission of 233U and 235U." EPJ Web of Conferences 239 (2020): 05008. http://dx.doi.org/10.1051/epjconf/202023905008.

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The analysis of angular and energy distributions of prompt neutrons from the thermal neutron induced fission of 233U and 235U measured recently in the WWR-M research reactor (Gatchina, Russia) have been performed. The yield of “scission” neutrons has been estimated by comparing the measured distributions with calculations within the model of emission of neutrons from completely accelerated fragments. Besides taking into account “scission” neutrons, for the best description of measured angular and energy distributions of fission neutrons, the calculation should be performed under the assumption that neutrons with a higher (7-9%) probability are emitted along the fission axis in the center-of-mass system of fission fragments.
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Lovell, A. E., T. Kawano, S. Okumura, M. R. Mumpower, I. Stetcu, and P. Talou. "The Extension of the Hauser-Feshbach Fission Fragment Decay Model to Multi-chance Fission and its Application to 239Pu." EPJ Web of Conferences 284 (2023): 04015. http://dx.doi.org/10.1051/epjconf/202328404015.

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The Hauser-Feshbach fission fragment decay model, HF3D, calculates the statistical decay of fission fragments through both prompt and delayed neutron and γ-ray emissions in a deterministic manner. While previously limited to the calculation of only first-chance fission, the model has recently been extended to include multi-chance fission, up to neutron incident energies of 20 MeV. The deterministic decay takes as input prescission quantities–fission probabilities, pre-fission neutron energies, and the average energy causing fission– and post-scission quantities–yields in mass, charge, total kinetic energy, spin, and parity. From those fission fragment initial conditions, the full decay is followed through both prompt and delayed particle emissions. The evaporation of the prompt neutrons and γ rays is calculated through the Hauser-Feshbach statistical theory, taking into account the competition between neutron and γ-ray emission, conserving energy, spin, and parity. The delayed emission is taken into account using time-independent calculation using decay data. This whole formulation allows for the calculation of prompt neutron and γ-ray properties, such as multiplicities and energy distributions, both independent and cumulative fission yields, and delayed neutron observables, in a consistent framework. Here, we describe the implementation of multi-chance fission into the HF3D model, and show an example of prompt and delayed quantities beyond first-chance fission, using the example of neutron-induced fission on 239Pu. This expansion represents significant progress in consistently modeling the emission of prompt and delayed particles from fissile systems.
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Fujio, Kazuki, Ali Al-Adili, Fredrik Nordström, Jean-François Lemaître, Shin Okumura, Satoshi Chiba, and Arjan Koning. "Prompt-fission observable and fission yield calculations for actinides by TALYS." EPJ Web of Conferences 292 (2024): 08004. http://dx.doi.org/10.1051/epjconf/202429208004.

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The nuclear reaction code TALYS adopts the Hauser-Feshbach statistical decay theory, to de-excite fission fragments. This involves for instance the evaporation of prompt fission neutrons and γ-rays. TALYS incorporates databases of primary fission fragment distribution which consists of primary fission fragment yield and data for excitation energy distribution of fission fragments. We conducted a sensitivity study on three parameters in TALYS and fitted them in order to reproduce experimental and evaluated data, in thermal neutron-induced fission of 235U. Moreover, we demonstrate a large-scale calculation of average prompt neutron and γ-ray multiplicities for 243 selected actinide isotopes.
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Qi, L., J. N. Wilson, M. Lebois, A. Al-Adili, A. Chatillon, D. Choudhury, A. Gatera, et al. "Prompt fission gamma-ray emission spectral data for 239Pu(n,f) using fast directional neutrons from the LICORNE neutron source." EPJ Web of Conferences 169 (2018): 00018. http://dx.doi.org/10.1051/epjconf/201816900018.

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Prompt fission gamma-ray spectra (PFGS) have been measured for the 239Pu(n,f) reaction using fast neutrons at Ēn=1.81 MeV produced by the LICORNE directional neutron source. The setup makes use of LaBr3 scintillation detectors and PARIS phoswich detectors to measure the emitted prompt fission gamma rays (PFG). The mean multiplicity, average total energy release per fission and average energy of photons are extracted from the unfolded PFGS. These new measurements provide complementary information to other recent work on thermal neutron induced fission of 239Pu and spontaneous fission of 252Cf.
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Seleznev, E., V. Bereznev, and I. Chernova. "PARTIAL NEUTRON TRANSPORT EQUATIONS." PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. SERIES: NUCLEAR AND REACTOR CONSTANTS 2019, no. 3 (September 26, 2019): 143–52. http://dx.doi.org/10.55176/2414-1038-2019-3-143-152.

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To analyze the spatial kinetics of the reactor, a system of equations for the spatial kinetics of the reactor, consisting of two equations, is usually used. One of them describes the behavior of the neutron flux density, and the second describes the behavior of the precursors of delayed neutrons. In this case, the density of the neutron flux includes the flux density prompt neutrons, appearing directly upon fission of the nucleus, and delayed neutrons that appear in the decay of some fission fragments. This system of equations is called classical. This paper considers the possibility of representing the neutron flux density in a nonstationary process by individual equations for prompt and delayed neutrons and presents the initial results of modeling the nonstationary process for dumping a control rod in a fast medium-power reactor. A system of equations describing such a behavior of the neutron field in a reactor is called a system of partial equations.
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Dissertations / Theses on the topic "Neutrons Prompts de Fission"

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Sardet, Alix. "Spectres en énergie des neutrons prompts de fission : optimisation du dispositif expérimental et application à l'²³⁸U." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS002/document.

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La fission nucléaire est un phénomène complexe dont tous les mécanismes ne sont pas entièrement compris. Dans le cadre d'une coopération internationale, le CEA/DAM/DIF étudie les spectres en énergie des neutrons prompts émis lors de la fission induite par des neutrons rapides, et plus particulièrement la zone à basse énergie de ces spectres (<1 MeV). Ce travail de thèse a consisté à optimiser un dispositif expérimental de mesure de neutrons prompts de fission. Dans un premier temps, de nouveaux détecteurs de fission ont été développés. Nous en rapportons ici la conception et étudions leurs performances en termes de discrimination alpha-fission, de résolution en temps et de distorsion sur le spectre mesuré. Le second axe de développement abordé au cours de cette thèse est celui de la détection des neutrons. Plusieurs types de détecteurs ont été comparés (discrimination neutron-gamma, efficacité de détection), en vue d'optimiser la détection des neutrons de basse énergie (<1 MeV). Ce mémoire présente les résultats de ces études. Enfin, le dispositif expérimental ainsi optimisé est utilisé pour mesurer le spectre en énergie des neutrons prompts émis lors de la fission induite par neutrons de l' ²³⁸UU. Après avoir présenté la méthode utilisée pour l'analyse des données, les résultats obtenus sont interprétés en termes de modèles et d'évaluations
The nuclear fission is a complex phenomenon whose mechanisms are not fully understood. Within the framework of an international cooperation, the CEA/DAM/DIF is taking part in the study of prompt fission neutron energy spectra from fast neutron induced fission, focusing on the low energy domain of these spectra (<1 MeV). This PhD was dedicated to the optimization of the experimental setup. New fission detectors were developed. We report on their conception and their performances in terms of alpha-fission discrimination, timing resolution and distortion on the measured spectrum. In a second step, several neutron detectors were studied (neutron-gamma discrimination, detection efficiency), so as to optimize the detection of low energy neutrons (<1 MeV). In the present document, we report on the results of this comparative study. Finally, the optimized experimental setup was used to measure prompt fission neutron energy spectra for the fast-neutron induced fission of ²³⁸U. After detailing the data analysis method, the results are interpreted in terms of models and evaluations
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Berge, Léonie. "Contribution à la modélisation des spectres de neutrons prompts de fission .Propagation d'incertitudes sur un calul de fluence cuve." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI039/document.

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Le spectre des neutrons prompts de fission (PFNS) est une donnée très importante pour diverses applications de la physique nucléaire. Cependant, en dehors du spectre de la fission spontanée du 252Cf, qui est reconnu comme un standard international et est utilisé pour la métrologie, le PFNS reste mal connu pour la plupart des noyaux fissionnants. En particulier, pour la fission rapide (induite par un neutron de plus de 100 keV environ), il existe peu de mesures, et les évaluations internationales présentent de fortes contradictions. De plus, il existe très peu de données sur les covariances associées aux diverses évaluations du spectre. Dans cette thèse, trois aspects de l'évaluation du PFNS sont abordés. Le premier aspect est la modélisation du spectre via le code FIFRELIN, développé au CEA Cadarache, qui simule la chaine de désexcitation des fragments de fission par émissions successives de neutrons et gammas prompts par la méthode de Monte-Carlo. Ce code a pour vocation de calculer les observables de fission dans un même calcul cohérent, à partir des distributions en masse, en énergie cinétique et en spin des fragments de fission. FIFRELIN a donc un caractère prédictif que n'ont pas les modèles analytiques utilisés pour décrire le PFNS. Une étude des paramètres de modèle influents, notamment le paramètre de densité de niveaux, est mené afin de tenter de mieux reproduire le spectre. Le deuxième aspect de la thèse concerne l'évaluation du PFNS et de sa matrice de covariance. On propose une méthodologie pour évaluer le spectre et sa matrice de covariance de manière rigoureuse, à travers l'outil CONRAD du CEA Cadarache. Ceci implique la modélisation du spectre à travers des modèles simples, notamment celui de Madland-Nix qui est le plus utilisé dans les évaluations, en ajustant les paramètres de ces modèles afin de reproduire les données expérimentales. La matrice de covariance provient de la propagation rigoureuse des sources d'incertitude qui interviennent dans le calcul. En particulier, les incertitudes systématiques liées au dispositif expérimental sont propagées par des techniques de marginalisation. La marginalisation permet de propager ces incertitudes sur le spectre calculé, en obtenant des incertitudes réalistes sans besoin d'être artificiellement rehaussées comme c'est souvent le cas dans le cadre d'ajustements bayésiens. La propagation de ces incertitudes expérimentales impacte aussi la matrice de corrélation du spectre calculé. On présente les résultats pour la fission induite par neutron thermique de l'235U et du 239Pu. Pour le modèle de Madland-Nix avec section inverse constante, l'énergie moyenne des neutrons prompts obtenue est de 1.979 MeV pour l'235U, et de 2.087 MeV pour le 239Pu. Le dernier aspect de la thèse est l'étude de l'impact du PFNS et de ses covariances sur le calcul du flux neutronique sur la cuve d'un réacteur. L'enjeu est de taille, car l'estimation de la fluence au niveau de la cuve d'un réacteur détermine l'intégrité de celle-ci, et donc la durée de vie du réacteur. On observe l'importance des termes de corrélations du spectre pour calculer notamment l'incertitude sur le flux intégré au-dessus de 1 MeV, de l'ordre de 6% (incertitude due seulement au spectre)
The prompt fission neutron spectrum (PFNS) is very important for various nuclear physics applications. Yet, except for the 252Cf spontaneous fission spectrum which is an international standard and is used for metrology purposes, the PFNS is still poorly known for most of the fissionning nuclides. In particular, few measurements exist for the fast fission spectrum (induced by a neutron whose energy exceeds about 100 keV), and the international evaluations show strong discrepancies. There are also very few data about covariances associated to the various PFNS evaluations. In this work we present three aspects of the PFNS evaluation. The first aspect is about the spectrum modeling with the FIFRELIN code, developed at CEA Cadarache, which simulates the fission fragment de-excitation by successive emissions of prompt neutrons and gammas, via the Monte-Carlo method. This code aims at calculating all fission observables in a single consistent calculation, starting from fission fragment distributions (mass, kinetic energy and spin). FIFRELIN is therefore more predictive than the analytical models used to describe the spectrum. A study of model parameters which impact the spectrum, like the fragment level density parameter, is presented in order to better reproduce the spectrum. The second aspect of this work is about the evaluation of the PFNS and its covariance matrix. We present a methodology to produce this evaluation in a rigorous way, with the CONRAD code, developed at CEA Cadarache. This implies modeling the spectrum through simple models, like the Madland-Nix model which is the most commonly used in the evaluations, by adjusting the model parameters to reproduce experimental data. The covariance matrix arises from the rigorous propagation of the sources of uncertainty involved in the calculation. In particular, the systematic uncertainties arising from the experimental set-up are propagated via a marginalization technique. The marginalization allows propagating these uncertainties on the calculated spectrum, and obtaining realistic uncertainties without having to artificially raise them, as it is sometimes necessary in Bayesian adjustments. The experimental uncertainty propagation also impacts the spectrum correlation matrix. We present the result for thermal neutron-induced fission of 235U and 239Pu. For the Madland-Nix model with constant inverse cross-section, the prompt neutron mean energy is 1.979 MeV for 235U and 2.087 MeV for 239Pu. The last aspect of this work is the calculation of the impact of the PFNS and its covariance matrix on a reactor vessel flux. This calculation is of major importance, since the vessel fluence estimation determines the vessel integrity, and therefore determines the reactor lifetime. We observe the importance of the PFNS correlation terms, to compute in particular the vessel flux uncertainty above 1 MeV, which is of the order of 6% (uncertainty only due to PFNS)
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Qi, Liqiang. "Measurements of Prompt Gamma Rays Emitted in Fission of ²³⁸U and ²³⁹ Pu Induced by Fast Neutrons from the LICORNE Neutron Source." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS320/document.

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Les spectres des rayons γ prompt de fission sont des données nucléaires importantes pour la physique des réacteurs, en tant qu'entrée pour les calculs de chauffage gamma, puisque l'effet de chauffage gamma peut être sous-estimé jusqu'à ~28% avec les données nucléaires actuelles. De plus, les nouvelles informations sur les rayons γ prompts de fission seront utiles du point de vue de la physique fondamentale, où les résultats peuvent être comparés à de nombreuses prédictions théoriques concurrentes pour affiner les modèles du processus de fission. Les spectres des rayons γ prompts de fission ont été mesurés pour la fission induite par neutrons rapides de ²³⁸U et de ²³⁹Pu, en utilisant des neutrons rapides générés à partir de la source LICORNE. Le dispositif expérimental se composait d'une chambre d'ionisation et de différents types de détecteurs à scintillation, dont les détecteurs LaBr₃ et PARIS phoswich. Une procédure d'analyse, comprenant le unfolding et la simulation de la réponse aux rayons γ dans les détecteurs à scintillation, est mise au point pour extraire le spectre des rayons γ prompts de fission et les caractéristiques spectrales correspondantes. Les résultats expérimentaux sont comparés aux codes de modélisation de fission GEF et FREYA. Cette comparaison révèle que les caractéristiques spectrales sont liées aux conditions énergétiques, aux rendements isotopiques et au moment angulaire des fragments de fission. La dépendance énergétique des caractéristiques spectrales montre que l'émission des rayons γ est tout à fait insensible à l'énergie neutronique incidente. Toutefois, on observe une forte dépendance à l'égard du système fissionnant particulier
Prompt fission γ-ray spectra are important nuclear data for reactor physics, as an input for gamma heating calculations, since the gamma heating effect can be under-estimated by up to ~28% with present nuclear data. Furthermore the new prompt fission γ-ray information will be useful from a fundamental physics point of view, where results can be compared with many competing theoretical predictions to refine models of fission process. Prompt fission γ-ray spectra have been measured for the fast-neutron-induced fission of ²³⁸U and ²³⁹PuPu, using fast neutrons generated from the LICORNE source. The experimental setup consisted of an ionization chamber and different types of scintillation detectors, including LaBr₃ and PARIS phoswich detectors. An analysis procedure, including unfolding and recovering the γ-ray response in the scintillation detectors, is developed to extract the prompt fission γ-ray spectrum and corresponding spectral characteristics. The experimental results are compared to the fission modeling codes GEF and FREYA. This comparison reveals that the spectral characteristics are related to the energetic conditions, isotopic yields and angular momentum of the fission fragments. The energy dependence of the spectral characteristics shows that the prompt γ-rays emission is quite insensitive to the incident neutron energy. However, a strong dependence on the particular fissioning system is observed
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Varapai, Natallia. "Développement d'un dispositif expérimental basé sur la digitalisation des signaux et dédié à la caractérisation des fragments de fission et des neutrons prompt[s] émis." Bordeaux 1, 2006. http://www.theses.fr/2006BOR13274.

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Ce travail de thèse décrit la mise en place d'un dispositif expérimental basé sur la digitalisation des signaux et dédié à l'étude des neutrons prompts de fission émis en coincidence avec les fragments de fission lors de la fission spontane��e du 252Cf. Ce dispositifcomprend une chambre à ionisation utilisée pour la détection des fragments de fission ainsi qu'un scintillateur liquide de type NE213 pour la détection des neutrons prompts. Nous montrons comment l'analyse délicate des signaux digitalisés nous a permis de déterminer à la fois les distributions en masse et en énergie cinétique des fragments de fission ainsi que le spectre en energie et la multiplicité des neutrons de fission.
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Rąpała, Michał. "Etude de la fission nucléaire par spectrométrie des rayons gamma prompts." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS390/document.

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La volonté d'améliorer l'efficacité énergétique des réacteurs nucléaires a motivé de nouvelles solutions dans leur conception. L'une d'elles est l’utilisation d’un réflecteur lourd dans les réacteurs de génération III+ et les futurs réacteurs de génération IV. Lorsque la matière est traversée par des rayons γ, les excitations induites entraînent une élévation de sa température. Ce processus, appelé échauffement γ, est responsable de plus de 90% de la production de chaleur dans la région hors combustible d'un réacteur nucléaire. C’est également le cas dans le réflecteur. Pour simuler l'effet de l’échauffement γ en fonction de la composition du combustible, il faut disposer de données précises sur les γ prompts émis par les différents fragments produits dans le processus de fission. En 2012, une campagne d’expériences inédite, EXILL, a été menée au réacteur de recherche de l'ILL. Un grand nombre de détecteurs HPGe a été placé autour d’une cible fissile et a mesuré les rayons γ émis par la cible alors qu’elle était irradiée par un faisceau intense de neutrons froids. Dans ce travail, nous avons analysé les données obtenues avec des cibles ²³⁵U. Elles nous ont permis d’étudier la désexcitation de plusieurs fragments de fission et plus globalement le processus de fission induite par des neutrons. Dans un premier temps, nous avons utilisé la méthode standard d'analyse par coïncidence γ-γ-γ. Nous avons pu filtrer les données expérimentales, identifier les transitions γ dans des fragments bien produits et calculer leur intensité relative. Les problèmes que nous avons rencontrés concernent le bruit de fond. Les résultats obtenus dépendent de ce choix et présentent donc des problèmes de reproductibilité. Nous avons développé et testé une nouvelle méthodologie d'analyse. Son principe est un balayage des portes de coïncidence selon trois directions, ce qui permet de trouver le bruit de fond le mieux adapté. L'idée principale était finalement de passer d'une méthode "spectroscopique", dont le but est de trouver de nouvelles transitions et des états excités dans un noyau, à une méthode "spectrométrique", qui nous permet d'obtenir plus précisément l’intensité de transitions γ connues, avec une meilleure estimation de leur incertitude. Cela nous a amené à développer un logiciel d'analyse semi-automatique d'ajustement des pics. Divers schémas de calcul de l'intensité des transitions γ ont été également élaborés pour tenir compte des contaminations possibles, selon leur emplacement dans la matrice de coïncidence et leur intensité. La méthode standard et la nouvelle méthode d'analyse ont été comparées pour l'analyse du ¹⁴²Ba. Dans ce travail, nous avons également comparé nos résultats sur quelques noyaux, tel que le ¹⁰⁰Zr, avec des simulations réalisées avec le code FIFRELIN. Ce dernier est un code Monte-Carlo qui simule le processus de fission et la désexcitation des fragments de fission. FIFRELIN utilise plusieurs modèles différents pour décrire ces processus. Nous avons testé le comportement des différents modèles, trouvé les valeurs optimales des paramètres de simulation et testé comment ces configurations reproduisaient les résultats expérimentaux. FIFRELIN n'a pas été en mesure de reproduire simultanément les intensités des transitions γ émises par les fragments de ¹⁰⁰Zr et la multiplicité de neutrons prompts moyennée sur tous les fragments de fission. Cependant, avec des paramètres modifiés, FIFRELIN a fourni localement une multiplicité de neutrons prompts correcte pour les fragments de masse atomique A=100 et des intensités de transition γ bien reproduites pour le noyau de ¹⁰⁰Zr. Nous avons également comparé nos résultats expérimentaux sur les fragments de ¹⁰⁰Zr provenant du processus ²³⁵U(n,f) avec les autres données expérimentales disponibles provenant des expériences sur ²⁴⁸Cm(sf) et ²⁵²Cf(sf), et une autre expérience sur ²³⁵U(n,f)
The desire to improve the fuel efficiency of nuclear reactors has motivated new solutions in their design. One of them is the heavy reflector used in the generation III+ and in the future generation IV reactors. γ-rays passing through matter cause its excitation and temperature rise. It is a process called γ-heating, and it is responsible for more than 90% of the heat production in the non-fuel region of the nuclear reactor. This is also the case of the heavy reflector. To simulate the γ-heating effect in every state of the nuclear reactor it is necessary to have precise data on the prompt γ-rays emitted by different fission fragments produced in the course of the nuclear chain reaction. In 2012, at the research reactor of the ILL, an innovative experiment, called EXILL, was conducted. It produced a large amount of useful data on the de-excitation of the fission fragments. A large number of HPGe detectors were used to study the neutron induced fission process by measuring the emitted γ-rays. Fissile targets were irradiated by an intense cold neutron beam. In this work we analyzed the ²³⁵U targets. We studied several fission fragments and more generally the fission process by using high-resolution γ-ray spectroscopy. At the beginning, we used the standard γ-γ-γ coincidence analysis method. We were able to filter experimental data, identify the well produced γ-rays, and calculate their relative intensities. The problems we have encountered are related to the background. The results obtained with this method were background dependent and thus presented some problems with reproducibility. We therefore developed and tested a new analysis methodology. Its crucial feature is a coincidence gates scanning in three directions which helps to find the most suitable background. The idea was to move from a “spectroscopic” method, which main purpose is finding new transitions and excited states in a nucleus, to a “spectrometric” method, which allows us to obtain more precise γ-ray intensities. We developed a semi-automatic analysis software which facilitates fitting of the chosen γ-ray peak, the contamination and the background. Various γ-ray intensity calculation schemes were derived to take into account different contamination strengths and placements. The results of the analysis with the new technique are reproducible and more reliable. The standard and the new analysis method were compared in the ¹⁴²Ba analysis. In this work, we also compared our experimental results on some nuclei, such as ¹⁰⁰Zr, with the simulation results performed with the FIFRELIN code. It is a Monte-Carlo code which simulates the fission process and the de-excitation of the fission fragments. It uses various models to describe these processes. We were able to test the behavior of different models implemented in FIFRELIN to find the optimal simulation parameter values and to test how well these setups reproduce the experimental results. FIFRELIN was unable to simultaneously reproduce the γ-ray intensities of ¹⁰⁰Zr and the prompt-neutron multiplicity averaged over all fission fragments. However, with modified simulation parameters, FIFRELIN locally provided correct prompt-neutron multiplicity for the fission fragment with the atomic mass A=100 and well reproduced γ-ray intensities of ¹⁰⁰Zr. We also compared our experimental results on ¹⁰⁰Zr coming from the ²³⁵U(n,f) process with the other available experimental data coming from the experiments on ²⁴⁸Cm(sf) and ²⁵²Cf(sf), and another experiment on ²³⁵U(n,f)
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Tovar, Jesus Felipe. "Studies of prompt gamma and neutron yield due to 2.5 MeV neutrons using GEANT4." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.

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Martin, Julie-Fiona. "Coulex fission of ²³⁴U, ²³⁵U, ²³⁷Np and ²³⁸Np studied within the SOFIA experimental program." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112315/document.

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SOFIA (Studies On FIssion with Aladin - Études de fission avec ALADIN) est un projet expérimental qui se propose de mesurer systématiquement les rendements isotopiques de fission, ainsi que l'énergie cinétique totale des fragments, pour une large gamme de noyaux fissionnants. Le travail de thèse présenté ici prend part au projet SOFIA, et a pour objet l'étude de la fission de noyaux dans la région des actinides : ²³⁴U, ²³⁵U, ²³⁷Np et ²³⁸Np.L'expérience SOFIA est menée au GSI, un accélérateur d'ions lourds situé à Darmstadt en Allemagne. Cette installation fournit un faisceau relativiste et intense d'uranium-238. Par une réaction de fragmentation de ce faisceau primaire, il est créé un faisceau secondaire contenant une large variété d'ions, dont, pour certains, la fission va être étudiée. Les ions de ce faisceau secondaire sont triés et identifiés dans le séparateur de fragments FRS, un spectromètre de recul de haute résolution qui est réglé pour sélectionner les ions d'intérêt.Ensuite, les ions fissiles sélectionnés continuent leur vol jusqu'à la Cave-C, une aire expérimentale où l'expérience de fission elle-même a lieu. À l'entrée de la cave, l'ion du faisceau secondaire est excité par interaction Coulombienne alors qu'il traverse une cible; les voies de dé-excitation possibles incluent la fission de basse énergie. Lors d'une fission, les deux fragments sont émis dans un cône étroit dans le référentiel du laboratoire, dû à l'impulsion relativiste qui leur est transmise par le système fissionnant. Un spectromètre de recul complet a été développé par la collaboration SOFIA autour du dipôle existant ALADIN. L'identification des fragments est réalisée par des mesures de perte d'énergie, de temps de vol et de déviation dans l'aimant. Les deux fragments de fission sont identifiés simultanément et complètement (en masse et en charge). Ce document présente l'analyse menée pour (1) l'identification du système fissionnant, (2) l'identification des deux fragments de fission - évènements par évènements -, et (3) l'extraction des observables de fission : rendements, énergie cinétique totale, multiplicité total en neutrons prompts. Ces résultats concernant les actinides sont discutés, et l'ensemble des données extraites est fourni
SOFIA (Studies On FIssion with Aladin) is an experimental project which aims at systematically measuring the fission fragments' isotopic yields as well as their total kinetic energy, for a wide variety of fissioning nuclei. The PhD work presented in this dissertation takes part in the SOFIA project, and covers the fission of nuclei in the region of the actinides : ²³⁴U, ²³⁵U, ²³⁷Np and ²³⁸Np.The experiment is led at the heavy-ion accelerator GSI in Darmstadt, Germany. This facility provides intense relativistic primary beam of 238U. A fragmentation reaction of the primary beam permits to create a secondary beam of radioactive ions, some of which the fission is studied. The ions of the secondary beam are sorted and identified through the FR-S (FRagment Separator), a high resolution recoil spectrometer which is tuned to select the ions of interest.The selected - fissile - ions then fly further to Cave-C, an experimental area where the fission experiment itself takes place. At the entrance of the cave, the secondary beam is excited by Coulomb interaction when flying through an target; the de-excitation process involves low-energy fission. Both fission fragments fly forward in the laboratory frame, due to the relativistic boost inferred from the fissioning nucleus.A complete recoil spectrometer has been designed and built by the SOFIA collaboration in the path of the fission fragments, around the existing ALADIN magnet. The identification of the fragments is performed by means of energy loss, time of flight and deviation in the magnet measurements. Both fission fragments are fully (in mass and charge) and simultaneously identified.This document reports on the analysis performed for (1) the identification of the fissioning system, (2) the identification of both fission fragments, on an event-by-event basis, and (3) the extraction of fission observables: yields, TKE, total prompt neutron multiplicity. These results, concerning the actinides, are discussed, and the set of data extracted is provided
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Varapai, Nathallia. "Développement d'un dispositif expérimental basé sur ladigitalisation des signaux et dédié à la caractérisation desfragments de fission et des neutrons prompte émis." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2006. http://tel.archives-ouvertes.fr/tel-00404495.

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Ce travail de thèse décrit la mise en place d'un dispositif expérimental basé sur la digitalisation des signaux et dédié à l'étude des neutrons prompts de fission émis en coincidence avec les fragments de fission lors de la fission spontanée du 252Cf. Ce dispositif comprend une chambre à ionisation utilisée pour la détection des fragments de fission ainsi qu'un scintillateur liquide de type NE213 pour la détection des neutrons prompts. Nous montrons comment l'analyse délicate des signaux digitalisés nous a permis de déterminer à la fois les distributions en masse et en énergie cinétique des fragments de fission ainsi que le spectre en énergie et la multiplicité des neutrons de fission
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Abdelrahman, Y. S. "Prompt gamma-rays from fission fragments." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234192.

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McGinnis, Jason M. "PROMPT FISSION NEUTRON ENERGY SPECTRUM OF n+235U." UKnowledge, 2019. https://uknowledge.uky.edu/physastron_etds/63.

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Despite nuclear fission prominence in nuclear physics, there are still several fundamental open questions about this process. One uncertainty is the energy distribution of neutrons emitted immediately after fission. In particular the relative energy distribution of neutrons above 8~MeV has been difficult to measure. This experiment measured the prompt neutron energy spectrum of n+235U from 3-10~MeV. The measurement took place at Los Alamos National Laboratory (LANL) and used a double time-of-flight technique to measure both the beam and fission neutron kinetic energies. Fission event timing was measured with a parallel plate avalanche counter. The fission neutron time-of-flight was measured with 2~m long plastic scintillation detectors. By combining the time-of-flight information with a known flight path the kinetic energy spectrum of neutrons was measured. To eliminate backgrounds various time-of-flight and energy cuts were imposed and an accidental coincidence background was subtracted. An MCNP simulation, including the 2~m neutron detector geometry, was done using the Madland and Nix model as the input energy distribution for the simulated neutrons. Finally, the measured energy spectrum was compared with the MCNP simulated n+235U fission neutron energy spectrum.
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Books on the topic "Neutrons Prompts de Fission"

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Kornilov, Nikolay. Fission Neutrons. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-07133-6.

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H, Hamilton Joseph, Ramayya A. V, and Carter H. K, eds. Fission and properties of neutron-rich nuclei: Proceedings of the fourth International Conference, Sanibel Island, USA, 11-17 November 2007. Singapore: World Scientific, 2008.

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International Conference on Fission and Properties of Neutron-Rich Nuclei (4th 2007 Sanibel Island, Fla.). Fission and properties of neutron-rich nuclei: Proceedings of the fourth International Conference, Sanibel Island, USA, 11-17 November 2007. Edited by Hamilton Joseph H, Ramayya A. V, and Carter H. K. Singapore: World Scientific, 2008.

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Douglas, Grahn, Carnes Bruce A, Thomson John F, U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research. Division of Regulatory Applications., Argonne National Laboratory. Division of Biological and Medical Research., and Argonne National Laboratory, eds. Relative biological effectiveness (RBE) of fission neutrons and gamma rays at occupational exposure levels. Washington, DC: Division of Regulatory Applications, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1987.

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Italy) International Workshop on Fusion Neutrons and Subcritical Nuclear Fission (2011 Varenna. Fusion for neutrons and subcritical nuclear fission: Proceedings of the international conference : Varenna, Italy, 12-15 September 2011. Edited by Källne Jan. Melville, N.Y: American Institute of Physics, 2012.

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Afarideh, Hossein. A study of fission in [superior] 238 U induced by Monoenergetic neutrons and heavy ions and oflight particle emission in [superior] 252 Cf spontaneous fission. Birmingham: University of Birmingham, 1988.

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Kellett, Mark Adrian. Measurement of the absolute yield of delayed neutrons from the fast neutron induced fission of uranium 235 and 238. Birmingham: University of Birmingham, 1998.

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Kornilov, Nikolay. Fission Neutrons: Experiments, Evaluation, Modeling and Open Problems. Springer, 2014.

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Kornilov, Nikolay. Fission Neutrons: Experiments, Evaluation, Modeling and Open Problems. Springer, 2016.

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Kornilov, Nikolay. Fission Neutrons: Experiments, Evaluation, Modeling and Open Problems. Springer, 2014.

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Book chapters on the topic "Neutrons Prompts de Fission"

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Shen, Qing-Biao, and Ye Tian. "Fission Prompt Neutrons, Prompt γ Rays, and Fission Fragment Independent Yield." In Equilibrium Compound Nucleus Post-Fission Theory, 97–110. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-43316-0_7.

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Kornilov, Nikolay. "Introduction." In Fission Neutrons, 1–5. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07133-6_1.

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Kornilov, Nikolay. "Experiment." In Fission Neutrons, 7–43. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07133-6_2.

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Kornilov, Nikolay. "Microscopic Spectra Evaluation. Semiempirical Modeling." In Fission Neutrons, 45–75. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07133-6_3.

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Kornilov, Nikolay. "Physical Models." In Fission Neutrons, 77–112. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07133-6_4.

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Kornilov, Nikolay. "Achievements and Still Open Problems." In Fission Neutrons, 113–32. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07133-6_5.

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Khokhlov, Yu A., I. A. Ivanin, Yu I. Vinogradov, V. I. In’kov, L. D. Danilin, V. I. Panin, and V. N. Polynov. "Measurements of Energy Dependence of Average Number of Prompt Neutrons from Neutron-Induced Fission of 235U, 241Am and 243Am From 0.5 to 12 MeV." In Nuclear Data for Science and Technology, 51–53. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-58113-7_12.

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Conrad, Harald. "Spallation – Neutrons Beyond Nuclear Fission." In Handbook of Particle Detection and Imaging, 719–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-13271-1_30.

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Conrad, Harald. "Spallation – Neutrons Beyond Nuclear Fission." In Handbook of Particle Detection and Imaging, 1–40. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-319-47999-6_30-2.

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Younes, Walid, and Walter D. Loveland. "Fission neutrons and gamma rays." In Graduate Texts in Physics, 89–113. Cham: Springer International Publishing, 2012. http://dx.doi.org/10.1007/978-3-030-84592-6_5.

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Conference papers on the topic "Neutrons Prompts de Fission"

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Talou, P., Audrey Chatillon, Herbert Faust, Gabriele Fioni, Dominique Goutte, and Héloise Goutte. "Advanced modeling of prompt fission neutrons." In 4TH INTERNATIONAL WORKSHOP ON NUCLEAR FISSION AND FISSION-PRODUCT SPECTROSCOPY. AIP, 2009. http://dx.doi.org/10.1063/1.3258234.

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Ruddy, Frank H., John G. Seidel, and Robert W. Flammang. "Prompt Pulsed Neutron Activation Analysis for Detection of Fission Neutrons." In 2006 IEEE Nuclear Science Symposium Conference Record. IEEE, 2006. http://dx.doi.org/10.1109/nssmic.2006.356112.

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CHATILLON, A., T. GRANIER, J. TAIEB, G. BELIER, B. LAURENT, S. NODA, R. C. HAIGHT, M. DEVLIN, R. O. NELSON, and J. M. O'DONNELL. "ENERGY MEASUREMENT OF PROMPT FISSION NEUTRONS IN 239PU(N,F) FOR INCIDENT NEUTRON ENERGIES FROM 1 TO 200 MEV." In Seminar on Fission. WORLD SCIENTIFIC, 2010. http://dx.doi.org/10.1142/9789814322744_0018.

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Cherubini, N., A. Dodaro, G. Gandolfo, L. Lepore, G. A. Marzo, E. Piccinelli, and R. Remetti. "The Neutron Active Interrogation System for In-Field Detection of Transuranic-Based Radioactive Dispersal Devices for Security Applications." In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81422.

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The increasing of terror menace in recent years led the international community to enhance the efforts to minimize threats to people in everyday life by developing devices, techniques, and procedures targeted to improve the collective security. In this framework the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) developed a new device to improve CBRNe resilience, the Neutron Active Interrogation system (NAI). It has been conceived and optimized to identify transuranic-based Radioactive Dispersal Devices potentially hidden in packages, envisaging its utilization in field applications. NAI is based on the detection of neutrons from induced fission on small amount, of the order of a few grams, of fissile material. The device exploits a portable neutron generator based on d-t fusion reaction, a polyethylene structure for reducing the neutron energy in order to maximize the fission cross-section, and an array of 3He proportional counters. Fissile material detection is made using the Differential Die-Away time Analysis (DDAA), an active neutron technique based on the difference among the die-away times of fast interrogation neutrons and prompt fission neutrons induced by thermal neutrons in the moderating system. The original experimental setup was tested on the field during the live demo open to the public at the EDEN Project Demonstration occurred in September 2015 at ENEA Frascati Research Centre in Rome. Since then, the setup has been modified to improve the device detection capabilities. NAI performances have been tested within different environmental conditions, e.g. open field geometry vs. bunker-like geometry, to study the effects of scattering phenomena. The optimized configuration here presented is transportable, lightweight, and able to detect 2 grams of 235U contained in a salt of depleted uranium in real time, independently from the measurement environmental conditions.
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Sailaubekov, Bekzat, Andrey V. Isaev, Alexander I. Svirikhin, Roman S. Mukhin, Maxim L. Chelnokov, Victor I. Chepigin, Haleshappa M. Devaraja, et al. "Prompt neutrons accompanying the spontaneous fission of 250No." In THE IV INTERNATIONAL SCIENTIFIC FORUM “NUCLEAR SCIENCE AND TECHNOLOGIES”. AIP Publishing, 2024. http://dx.doi.org/10.1063/5.0193489.

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Khokhlov, Yurii A., Igor A. Ivanin, Valerii I. In’kov, and Lev D. Danilin. "Measurements of energy dependence of average number of prompt neutrons from neutron-induced fission of [sup 242]Pu from 0.5 to 10 Mev." In The second international workshop on nuclear fission and fission-product spectroscopy. AIP, 1998. http://dx.doi.org/10.1063/1.56695.

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TALOU, P. "AT AND BEYOND THE SCISSION POINT: WHAT CAN WE LEARN FROM SCISSION AND PROMPT NEUTRONS?" In Seminar on Fission VI. WORLD SCIENTIFIC, 2008. http://dx.doi.org/10.1142/9789812791061_0013.

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Talou, P., T. Kawano, L. Bonneau, Jutta Escher, Frank S. Dietrich, Toshihiko Kawano, and Ian J. Thompson. "Prompt Fission Neutrons as Probes to Nuclear Configurations at Scission." In COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS: Proceedings of the 2007 International Workshop on Compound-Nuclear Reactions and Related Topics - CNR∗ 2007. AIP, 2008. http://dx.doi.org/10.1063/1.2920730.

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Maslov, V. M. "Multiplicities and Spectra of Prompt-Fission Neutrons up to 200 MeV." In INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY. AIP, 2005. http://dx.doi.org/10.1063/1.1945006.

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TALOU, P., T. KAWANO, and I. STETCU. "MONTE CARLO HAUSER-FESHBACH CALCULATIONS OF PROMPT FISSION NEUTRONS AND GAMMA RAYS." In Proceedings of the Fifth International Conference on ICFN5. WORLD SCIENTIFIC, 2013. http://dx.doi.org/10.1142/9789814525435_0070.

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Reports on the topic "Neutrons Prompts de Fission"

1

Haight, Robert C. Scission Neutrons in Spontaneous and Neutron-Induced Fission: Effect on Prompt Fission Neutron Spectra. IAEA Nuclear Data Section, February 2020. http://dx.doi.org/10.61092/iaea.6fxg-n58v.

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This consultant was asked to look into the possibility of so-called “scission neutrons”, that is neutrons emitted in the fission process before full acceleration of the two large fragments. Results of new measurements that measure neutron emission relative to the direction of the fragments are available, and the quantification of scission neutron has been derived from these data. More detailed models of the fission process are also new. It is however the conclusion of this consultant that the existence of scission neutrons has not been proven from experimental data. Further, the possibility of some pre-equilibrium process producing high energy neutrons in spontaneous fission or in fission induced by low energy neutrons is also not confirmed. Recommendations are made, with a principal one being that detailed modelling of neutron scattering in the analysis of experimental data is of utmost importance. The data base that pertains to scission neutrons and pre-equilibrium neutrons from the fission process is limited, although the recent experimental data could be mined for more information .
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Vorobyev, A. S., and O. A. Shcherbakov. Scission Neutrons from Thermal Neutron induced Fission of 239-Pu and Spontaneous Fission of 252-Cf. IAEA Nuclear Data Section, February 2020. http://dx.doi.org/10.61092/iaea.8t4w-essq.

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The properties of “scission” neutrons from thermal-neutron induced fission of 239Pu(nth,f) and spontaneous fission of 252Cf(sf) were obtained by comparing experimental angular and energy distributions of the prompt fission neutrons measured recently at PNPI with model distributions calculated under the assumption that all prompt fission neutrons are emitted from fully accelerated fragments.
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Vorobyev, A. S., and O. A. Shcherbakov. Experimental Investigation of the Properties of Scission Neutrons In Thermal-Neutron Induced Fission of 233U and 235U. IAEA Nuclear Data Section, February 2020. http://dx.doi.org/10.61092/iaea.7zgq-zwwx.

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The properties of “scission” neutrons from thermal neutron induced fission of 233U and 235U were obtained by comparing experimental angular and energy distributions of the prompt fission neutrons measured recently at PNPI with model distributions calculated under the assumption that all prompt fission neutrons are emitted from fully accelerated fragments. To obtain model distributions, it is assumed to use the spectra of prompt fission neutrons measured at small angles relative to the preferential direction of movement of light and heavy fragments because it is expected that just for these angles the contribution of non-primary mechanism is minimal while a contribution of neutrons emitted by complementary fragment can be taken into account correctly. It is also very important that in this approach it is possible to obtain the model distributions practically unlimited in low-energy range.
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4

Noguere, Gilles, Oscar Cabellos, Denise Neudecker, Andrej Trkov, and Roberto Capote Noy. Summary Report of the IAEA Consultants’ Meeting of the International Nuclear Data Evaluation Network (INDEN) on Actinide Evaluation in the Resonance Region (4). IAEA Nuclear Data Section, September 2022. http://dx.doi.org/10.61092/iaea.kw6h-tcge.

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A Consultants’ Meeting on Actinide Evaluation in the Resonance Region (4) of the International Nuclear Data Evaluation Network (INDEN) was held as a hybrid meeting from 1 to 4 November 2021. The meeting was a follow-up of the working group on evaluations in the resonance region of actinide nuclei. On-going evaluation work on 233U, 238U, 235U and 239Pu was discussed. Particular attention was paid to Prompt Fission Neutron Spectra, neutron multiplicities and reference integrals for fission cross sections were proposed for TOF fission data of fissile targets.
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5

Talou, Patrick, Toshihiko Kawano, and Ionel Stetcu. Monte Carlo Hauser-Feshbach Calculations of Prompt Fission Neutrons and Gamma Rays: Application to Thermal Neutron-Induced Fission Reactions on U-235 and Pu-239. Office of Scientific and Technical Information (OSTI), September 2012. http://dx.doi.org/10.2172/1052775.

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6

Talou, Patrick, Bjorn Becker, Yaron Danon, Toshihiko Kawano, and Ionel Stetcu. Uncertainty Quantification with Monte Carlo Hauser-Feshbach Calculations of Prompt Fission Neutrons and Gamma Rays. Office of Scientific and Technical Information (OSTI), September 2012. http://dx.doi.org/10.2172/1052776.

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7

Neudecker, Denise. Evaluated Mean Values and Covariances for the Prompt Fission Neutron Spectrum of 239Pu induced by neutrons of 500 keV. Office of Scientific and Technical Information (OSTI), July 2014. http://dx.doi.org/10.2172/1136938.

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8

Simakov, S. Evaluation of the Prompt Gamma-ray Spectrum from Spontaneous Fission of 252Cf. IAEA Nuclear Data Section, February 2024. http://dx.doi.org/10.61092/iaea.bz1p-e3yc.

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The energy spectra, multiplicities and average energies of the prompt, total and delayed γ-rays accompanying the spontaneous fission of 252Cf were collected from the literature and dedicated databases. They were carefully analysed for consistency with a view to producing reference data for usage in various applications. This could be accomplished for the prompt fission gamma ray spectrum up to 20 MeV since dozens of measurements exist and reasonably agree. The prompt fission gamma ray spectrum (PFGS) was non-model evaluated by fitting the preselected experimental data with the help of the generalized least-squares (GLS) code GMA. The resulting spectrum could be considered as a reference for the γ-ray energies from 0.1 to 20 MeV with uncertainties varying between ≈ 3 and 25%. This reference gamma spectrum will be a substantial contribution to the precise and complete characterisation of the 252Cf source since the prompt fission neutron spectrum (PFNS), which has been accepted as a standard for a long time, has comparable uncertainties. The average gamma multiplicity and energy were also surveyed and used to derive the recommended values. The prompt X- and γ-ray energy spectra below ≈ 100 keV and delayed photon spectra in the whole energy range, as well as their multiplicities, are still seldomly and incompletely measured, that excepts an evaluation based on experimental data. The comparison with existing theoretical prompt and delayed 252Cf(s.f.) γ-spectra or with those presented in the major evaluated cross section libraries explored their incompleteness or deviations from the evaluated PFGS. The existing measurements of the pionic and muonic radioactivity of 252Cf(s.f.) and 235U(nth,f) were reviewed and the potential impact of gammas from the π0 decay on the high energy part of the PFGS was investigated.
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9

Kelly, Keegan, Matthew Devlin, John O'Donnell, and Eames Bennett. Prompt Fission Neutron Detection and Neutron Scattering Measurements at WNR FP15L. Office of Scientific and Technical Information (OSTI), October 2021. http://dx.doi.org/10.2172/1827549.

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10

Neudecker, Denise. Introducing Nuclear Data Evaluations of Prompt Fission Neutron Spectra. Office of Scientific and Technical Information (OSTI), June 2015. http://dx.doi.org/10.2172/1186041.

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