Nucleon-induced reactions at intermediate energies: New data at 96 MeV and theoretical status

Double-differential cross sections for light charged particle production (up to A=4) were measured in 96 MeV neutron-induced reactions, at TSL laboratory cyclotron in Uppsala (Sweden). Measurements for three targets, Fe, Pb, and U, were performed using two independent devices, SCANDAL and MEDLEY. The data were recorded with low energy thresholds and for a wide angular range (20-160 degrees). The normalization procedure used to extract the cross sections is based on the np elastic scattering reaction that we measured and for which we present experimental results. A good control of the systematic uncertainties affecting the results is achieved. Calculations using the exciton model are reported. Two different theoretical approches proposed to improve its predictive power regarding the complex particle emission are tested. The capabilities of each approach is illustrated by comparison with the 96 MeV data that we measured, and with other experimental results available in the literature.Comment: 21 pages, 28 figure

Neutron-induced Light Ion Production From Fe, Pb And U At 96 Mev

Double-differential cross sections for light-ion production (up to A=4) induced by 96 MeV neutrons have been measured for $^{nat}$Fe, $^{nat}$Pb and $^{nat}$U. The experiments have been performed at the The Svedberg Laboratory in Uppsala, using two independent devices, MEDLEY and SCANDAL. The recorded data cover a wide angular range (20º - 160º) with low energy thresholds. The work was performed within the HINDAS collaboration studying three of the most important nuclei for incineration of nuclear waste with accelerator-driven systems (ADS). The obtained cross section data are of particular interest for the understanding of the so-called pre-equilibrium stage in a nuclear reaction and are compared with model calculations performed with the GNASH, TALYS and PREEQ code

A Novel Fast Neutron Detector For Nuclear Data Measurements

International audienceAccelerator driven system will use a heavy element target such as lead. Many calculations are available to simulate high-energy spallation neutron induced reactions, but little data are available for comparison with the simulations. In order to constrain the simulation tools we have measured (n,Xn) double differential cross section on different targets at The Svedberg Laboratory, Uppsala, Sweden. For neutron energy above 40 MeV, we have developed a novel detector, CLODIA, based on proton recoil and drift chambers to determine neutron energy. CLODIA (Chamber for LOcalization with DrIft and Amplification) is able to track recoil protons with energy up to 90 MeV with spatial resolution of about one millimeter and a detection efficiency of 99% for each drift chamber. Using CLODIA coupled with the SCANDAL set-up, we have been able to measure double differential (n,Xn) cross section on lead and iron for incident neutron energy in the 40-95 MeV energy region

Etude de la production de particules chargées dans des réactions induites par des neutrons de 96 MeV

Les réactions induites par des nucléons dans le domaine 20-200 MeV font depuis long temps l'objet d'une étude intensive. Le processus d'émission des particules dans la phase dite de pré-équilibre a une contribution très importante dans cette région et plusieurs approches théoriques ont été proposées afin de l'expliquer. Leur pouvoir prédictif doit être vérifiée par des comparaisons avec des données expérimentales dans diverses configurations. Les résultats expérimentaux présentés dans ce travail permettent l'extension vers les plus hautes énergies des bases de données, actuellement limitées aux énergies autour de 60 MeV. Réalisées au cyclotron du laboratoire TSL à Uppsala (Suède), les expériences ont comme objectif la mesure des sections efficaces doublement différentielles de production des particules chargées légères jusqu'au A=4 dans des réactions induites par des neutrons de 96 MeV sur trois systèmes, avec un seuil en énergie bas et dans un domaine angulaire important (20-160 degrés). La procédure de normalisation employée dans le calcul des sections efficaces utilise la réaction de diffusion élastique np. La détection des protons avec deux dispositifs expérimentaux indépendants (SCANDAL et MEDLEY) permet un bon control des erreurs systématiques affectant les résultats. Une étude systématique sur les prédictions des différents modèles théoriques est présentée dans la dernière partie de ce travail. A l'exception du modèle de simulation microscopique DYWAN, choisi pour son originalité dans le traitement des réactions nucléon-noyau, sont concernées généralement les approches implémentées dans des codes de simulation actuellement utilisés par la communauté scientifique.NI

Etude de la production de particules chargées dans des réactions induites par des neutrons de 96 MeV

CAEN-BU Sciences et STAPS (141182103) / SudocSTRASBOURG-Bib.Central Recherche (674822133) / SudocSudocFranceF

Mechanism of light cluster production in nucleon induced reactions at intermediate energy

A dynamical model dedicated to the nucleon induced reaction between 30 and 150 MeV is presented. It considers different stages of the reaction: the approaching phase, the in-medium nucleon-nucleon collisions, the cluster formation, and the secondary deexcitation process. The notions of influence area and phase-space exploration during the reaction are introduced. The importance of the reaction geometry and the conservation laws is emphasized. The model is able to globally reproduce the absolute cross sections for the emission of neutron and light charged particles for proton- and neutron induced reactions on heavy and intermediate targets ($^{56}$Fe and $^{208}$Pb)