Thematische Bibliographien / Prompt Fission Neutrons

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Auswahl der wissenschaftlichen Literatur zum Thema „Prompt Fission Neutrons“

Autor: Grafiati

Veröffentlicht am 25. Mai 2024

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Zeitschriftenartikel zum Thema "Prompt Fission Neutrons"

Lovell, A. E., P. Talou, I. Stetcu und 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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Stanescu, Razvan, Hadrick Green, Toby Morris, Gencho Rusev und 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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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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Lovell, A. E., T. Kawano, S. Okumura, M. R. Mumpower, I. Stetcu und 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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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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Oprea, Cristiana, Alexandru Mihul und 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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Fujio, Kazuki, Ali Al-Adili, Fredrik Nordström, Jean-François Lemaître, Shin Okumura, Satoshi Chiba und 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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Vorobyev, Alexander, Oleg Shcherbakov, Alexei Gagarski, Gennadi’ski Val und 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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Gatera, Angélique, Alf Göök, Franz-Josef Hambsch, André Moens, Andreas Oberstedt, Stephan Oberstedt, Goedele Sibbens, David Vanleeuw und Marzio Vidali. „Prompt fissionγ-ray characteristics from neutron-induced fission on 239Pu and the time-dependence of prompt-γray emission“. EPJ Web of Conferences 169 (2018): 00003. http://dx.doi.org/10.1051/epjconf/201816900003.

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Recent years have seen an increased interest in prompt fission γ-ray (PFG) measurements motivated by a high priority request of the OECD/NEA for high precision data, mainly for the nuclear fuel isotopes 235U and 239Pu. Our group has conducted a PFG measurement campaign using state-of-the-art lanthanum halide detectors for all the main actinides to a precision better than 3%. The experiments were performed in a coincidence setup between a fission trigger and γ-ray detectors. The time-of-flight technique was used to discriminate photons, traveling at the speed of light, and prompt fission neutrons. For a full rejection of all neutrons below 20 MeV, the PFG time window should not be wider than a few nanoseconds. This window includes most PFG, provided that no isomeric states were populated during the de-excitation process. When isomeric states are populated, PFGs can still be emitted up to 1 yus after the instant of fission or later. To study these γ-rays, the detector response to neutrons had to be determined and a correction had to be applied to the γ-ray spectra. The latest results for PFG characteristics from the reaction 239Pu(nth,f) will be presented, together with an analysis of PFGs emitted up to 200 ns after fission in the spontaneous fission of 252Cf as well as for thermal-neutron induced fission on 235U and 239Pu. The results are compared with calculations in the framework of the Hauser-Feshbach Monte Carlo code CGMF and FIFRELIN.

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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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Dissertationen zum Thema "Prompt Fission Neutrons"

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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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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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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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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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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Fondement, Valentin. „Conception d'une sonde diagraphique neutronique dans le cadre de l'exploration et de l'exploitation minière de l'uranium“. Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALY076.

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Cette thèse s’inscrit dans le cadre d’une collaboration entre le CEA et ORANO Mining avec pour objectif de développer une nouvelle sonde diagraphique basée sur l’interrogation neutronique active, dans le cadre de l’exploration et de l’exploitation de l’uranium dont une part importante de la production provient aujourd’hui de mines utilisant la lixiviation in situ. L’extraction chimique du minerai s’effectue directement dans le sol, sur plusieurs centaines de mètres, par injection et collection de solutions chimiques. Pour évaluer la rentabilité du puits, il est non seulement nécessaire de connaitre la quantité d’uranium disponible, mais aussi la perméabilité du milieu géologique. Cette dernière est déterminée en mesurant la « porosité hydrogène », à savoir la fraction volumique de la roche occupée par de l’eau, à l’aide de sondes qui émettent puis mesurent des neutrons ayant diffusé sur les noyaux d’hydrogène. L’uranium, et plus précisément son isotope 235, est aussi mesurable à l’aide de sondes équipées d’un générateur de neutrons pulsé. Ces travaux de recherche ont abouti à la conception d’une sonde permettant de réaliser ces deux mesures avec un unique compteur proportionnel à hélium 3 entouré de polyéthylène et blindé avec du cadmium. Des impulsions de neutrons de durée 50 µs sont émises par le générateur toutes les 5 ms (à 200 Hz). Puis, au cours des 800 µs qui suivent l’arrêt de chaque tir, on mesure les neutrons diffusés dans la formation qui ne sont pas thermalisés entièrement et peuvent encore franchir le blindage en cadmium. On obtient un comptage inversement proportionnel à la quantité d’hydrogène présente dans l’environnement. Sur les millisecondes qui suivent, les neutrons thermiques encore présents dans la roche font fissionner des noyaux d’235U, ce qui émet en moyenne 2.5 neutrons prompts par fission. Une partie de ces derniers sont mesurés par le bloc de détection, tandis que les neutrons du générateur, devenus thermiques 800 µs après l’arrêt du tir, ne peuvent plus franchir le blindage en cadmium. Grace à cette double discrimination, temporelle et énergétique, on peut mesurer le signal des neutrons prompts de fission qui est proportionnel à la concentration en uranium. Le flux de neutrons thermiques interrogateurs étant absorbé par l’hydrogène présent dans l’environnement, on utilise la porosité hydrogène mesurée pour corriger le signal des neutrons prompts de fission. Après avoir étudié par simulation Monte-Carlo les grandeurs affectant les performances de ces deux mesures (diamètre de forage, décentrage de la sonde, épaisseur et matériau de tubage, gangue de boue, lithologie), nous avons validé expérimentalement leur faisabilité en laboratoire. Tout d’abord, plusieurs chaines d’acquisition ont été testées pour pouvoir mesurer des taux de comptage instantanés de l’ordre de 106 s-1, pendant et juste après chaque tir du générateur de neutrons. D’autre part, une sonde maquette de laboratoire a été réalisée et testée dans un fût d’étalonnage rempli de 1.6 t de sable de Fontainebleau, spécialement conçu pour ces essais. Un bon accord entre l’expérience et les simulations a permis de valider la mesure de teneur en uranium et d’appréhender de nouveaux phénomènes, notamment l’activation de l’oxygène 17 responsable d’un bruit d’un fond actif significatif dans les formations siliceuses saturées en eau. La qualification des méthodes de calcul du signal et du bruit a été menée à bien, ce qui a permis d’estimer les performances prévues en situation réelle, notamment des limites de détection entre 10 et 200 ppm en 3 min de mesure pour des porosité hydrogènes respectives de 0 et 40%
This PhD in the frame of CEA - ORANO Mining collaboration, aims to develop a new logging tool, based on neutron active interrogation, in the scope of uranium exploration and exploitation. A large amount of its production comes from In situ recovery mines, by leaching chemically the ore in the ground over hundreds of meters. It is mandatory to determine the amount of uranium available, but also the permeability of the sand, to evaluate the profitability. This geological quantity can be assessed from the measurement of the porosity hydrogen that is the volume fraction of water in the rock formation. It is possible to measure this one by using neutron probes. Uranium, and especially its 235 isotope, can also be measured with that kind of logging tools, if they rely on a pulsed neutron generator. This research leads to a new probe design that allows performing the both measurements with a unique cadmium-shielded-helium 3-proportional counter. The generator emits a 50 µs neutron burst every 5 ms (at 200 Hz). In the 800 µs after the salvo we can measure the not-fully-thermalised neutrons, thanks to the cadmium shield acting like a filter. The obtained count is inversely proportional to the hydrogen, and water, environment content. Over the following milliseconds, thermal neutrons of the rock formation will lead to 235U nuclei fissions, which emit in average 2.5 prompt fission neutrons. A chunk of these neutrons is emitted toward our counter, as the neutrons from the generator, fully thermalized after 800 µs, cannot cross the cadmium. Thanks to that double energy-time discrimination, it is possible to measure the prompt fission neutron signal contribution, which is proportional to the uranium concentration. As thermal neutrons are absorbed by the hydrogen content in the environment, we can use the porosity hydrogen measurement to correct the prompt fission neutrons signal from its effect. Furthermore, a parametric study has been conducting, using the Monte-Carlo simulation code MCNP 6.1, to compare the quantities that affect the measurements performances (e.g. diameter, standoff, casing thickness, casing, mudcake thickness, lithology). Finally, the new measurement methods feasibility has been validated through two experimental campaigns: in one hand, the capability of the electronics to handle input count rates in the 106 s-1 yield, during and right after a pulse of the neutron D-T generator. In the other hand, a laboratory model of the neutron probe has been built and tested in a dedicated calibration drum, filled with 1.6 t Fontainebleau sand. An agreement between experiment and computer simulations has been found, which validates the uranium concentration measurement and allows the understanding of the main components of the active background. This study highlighted the contribution of the oxygen 17 activation delayed neutrons, in the water saturated sandstone environments. The signal and noise analysis method were qualified, leading to the first estimations of in situ performances, like the detection limit of the uranium concentration measurement, from 10 to 200 ppm for 3 min of acquisition, for hydrogen porosities ranging respectively from 0 to 40%

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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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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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Miller, Zachariah W. „A MEASUREMENT OF THE PROMPT FISSION NEUTRON ENERGY SPECTRUM FOR ²³⁵U(n,f) AND THE NEUTRON-INDUCED FISSION CROSS SECTION FOR ²³⁸U(n,f)“. UKnowledge, 2015. http://uknowledge.uky.edu/physastron_etds/29.

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Two measurements have been made, addressing gaps in knowledge for 235U(n,f) and 238U(n,f). The energy distribution for prompt fission neutrons is not well-understood below 1 MeV in 235U(n,f). To measure the 235U(n,f) prompt fission neutron distribution, a pulsed neutron beam at the WNR facility in Los Alamos National Laboratory was directed onto a 235U target with neutron detectors placed 1 m from the target. These neutron detectors were designed specifically for this experiment and employed a unique geometry of scintillating plastic material that was designed to reject backgrounds. Fission fragments were detected using an avalanche counter. Coincidences between fission fragment production and neutron detector events were analyzed, using a double time-of-flight technique to determine the energy of the prompt fission neutrons. A separate measurement was made, investigating the neutron-induced fission cross section for 238U(n,f). This measurement also used the pulsed neutron beam at the WNR facility. The neutron flux was normalized to the well-known hydrogen standard and the fission rate was observed for beam neutrons in the energy range of 130-300 MeV. Using an extrapolation technique, the energy dependence of the cross section was determined. These new data filled a sparsely populated energy region that was not well-studied and were measured relative to the hydrogen standard, unlike the majority of available data. These data can be used to constrain the fission cross section, which is considered a nuclear reaction standard.

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Buchteile zum Thema "Prompt Fission Neutrons"

Shen, Qing-Biao, und 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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Khokhlov, Yu A., I. A. Ivanin, Yu I. Vinogradov, V. I. In’kov, L. D. Danilin, V. I. Panin und 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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Capote, Roberto, und Andrej Trkov. „Predicting Spectrum Averaged Cross Sections in Prompt Fission Neutron Fields“. In Reactor Dosimetry: 16th International Symposium, 117–23. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2018. http://dx.doi.org/10.1520/stp160820170114.

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Shen, Wei, und Benjamin Rouben. „Approach to Criticality“. In Fundamentals of CANDU Reactor Physics, 93–100. ASME, 2021. http://dx.doi.org/10.1115/1.884836_ch9.

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Source neutrons are essential for reactor restart after a long shutdown. The term “source neutrons” applied to a particular time interval refers to a steady supply of neutrons, constant over the time interval of interest. This supply must be independent of the current or very recent fission rate, which can vary over the time interval. Thus, source neutrons exclude prompt neutrons and even delayed neutrons which originate in the fuel (i.e., those born in the fuel itself). This exclusion does not apply to delayed photoneutrons, which come from fissions that have occurred a long time before, and whose numbers are quite constant over the current time interval (further discussion of this point below).

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Montoya, Modesto. „Influence of Prompt Neutron Emission on the Final Distribution of Mass, Kinetic Energy, and Charge of Fragments from Actinide Fission“. In Nuclear Fission - From Fundamentals to Applications [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.110048.

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In nuclear fission of actinides samples, the fragments emit prompt neutrons before they reach the detectors. This chapter shows the effects of that emission on the final distribution of mass, charge, kinetic energy, and prompt neutron multiplicity of fragments. Those effects depend on the experimental technique. This chapter shows the curve of the maximal value of total kinetic energy as a function of primary fragment mass for the reactions 233U(nth, f), 235U(nth, f), and 239Pu(nth, f) which reflect the deformation properties of fragments in their ground states and the Coulomb effect on their scission configurations. The odd–even effects on the cold fission region will be also presented.

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Shen, Wei, und Benjamin Rouben. „Reactor Shutdown and Reactor Restart“. In Fundamentals of CANDU Reactor Physics, 101–12. ASME, 2021. http://dx.doi.org/10.1115/1.884836_ch10.

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The power referred to most frequently in reactor physics is neutron power. Neutron power is essentially the fission rate multiplied by the average prompt energy released and recovered per fission (see Section 2.1.2). It is also called “prompt” power, as it appears very quickly following fission. We cannot measure neutron power directly, but we do monitor the neutron flux with ion chambers located outside the calandria and in-core flux detectors. These neutronic signals are calibrated to the thermal-power measurement which allows neutron power to be derived.

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Konferenzberichte zum Thema "Prompt Fission Neutrons"

Talou, P., Audrey Chatillon, Herbert Faust, Gabriele Fioni, Dominique Goutte und 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 und 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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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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CHATILLON, A., T. GRANIER, J. TAIEB, G. BELIER, B. LAURENT, S. NODA, R. C. HAIGHT, M. DEVLIN, R. O. NELSON und 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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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 und 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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Cherubini, N., A. Dodaro, G. Gandolfo, L. Lepore, G. A. Marzo, E. Piccinelli und 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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Khokhlov, Yurii A., Igor A. Ivanin, Valerii I. In’kov und 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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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 und 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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Berichte der Organisationen zum Thema "Prompt Fission Neutrons"

Haight, Robert C. Scission Neutrons in Spontaneous and Neutron-Induced Fission: Effect on Prompt Fission Neutron Spectra. IAEA Nuclear Data Section, Februar 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., und O. A. Shcherbakov. Scission Neutrons from Thermal Neutron induced Fission of 239-Pu and Spontaneous Fission of 252-Cf. IAEA Nuclear Data Section, Februar 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., und O. A. Shcherbakov. Experimental Investigation of the Properties of Scission Neutrons In Thermal-Neutron Induced Fission of 233U and 235U. IAEA Nuclear Data Section, Februar 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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Talou, Patrick, Bjorn Becker, Yaron Danon, Toshihiko Kawano und 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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Talou, Patrick, Toshihiko Kawano und 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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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), Juli 2014. http://dx.doi.org/10.2172/1136938.

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Noguere, Gilles, Oscar Cabellos, Denise Neudecker, Andrej Trkov und 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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Simakov, S. Evaluation of the Prompt Gamma-ray Spectrum from Spontaneous Fission of 252Cf. IAEA Nuclear Data Section, Februar 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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Kelly, Keegan, Matthew Devlin, John O'Donnell und Eames Bennett. Prompt Fission Neutron Detection and Neutron Scattering Measurements at WNR FP15L. Office of Scientific and Technical Information (OSTI), Oktober 2021. http://dx.doi.org/10.2172/1827549.

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

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