Delayed neutrons measurement at the MEGAPIE target

In the framework of the Neutronic and Nuclear Assessment Task Group of the MEGAPIE experiment we measured the delayed neutron (DN) flux at the top of the target. The measurement was proposed mainly for radioprotection purposes since the DN flux at the top of the target has been estimated to be of the same order of magnitude as the prompt neutron flux. Given the strong model-dependence of DN predictions, the measurement of DN contribution to the total neutron activity at the top of the target was thus desired. Moreover, this measurement is complementary to the DN experiments performed at PNPI (Gatchina) on solid lead and bismuth targets. The DN measurement at MEGAPIE was performed during the start-up phase of the target. In this paper we present a detailed description of the experimental setup and some preliminary results on decay spectra.Comment: 4 pages, 4 figures, Proceedings of International Conference on Nuclear Data for Science and Technology (ND 2007), Nice, France, 22-27 Apr 200

Optimisation de combinaisons de faisceau et de cible pour les systèmes de réacteurs hybrides et pour la production de faisceaux radioactifs par fission

This thesis work consists of two parts: a) theoretical, and b) experimental. We combine and use the high energy transport code LAHET, the low energy transport code MCNP, and the activation code CINDER. Our benchmarking calculations show that LAHET neglects the Coulomb dissociation for deuterons. By adding this missing term, we obtain a good agreement with the available data. We also conclude that LAHET describes well the data for isotope production yields if the ORNL fission model is employed for nuclei with Z>90. The 'default' RAL fission model gives too broad isotopic distributions and fails to reproduce the data in absolute value. We examine different combinations of beams, beam energies, spallation target and multiplying medium materials in order to optimize the neutron production, energy amplification and isotope production via neutron induced fissions. We show that the (d,xn) reactions could bring a number of important advantages when compared to the (p,xn) reactions. We conclude that the use of deuterons instead of protons should result in higher primary beam intensities, lower costs of the system and facilitate radioprotection problems. Within the SPIRAL Phase-II project at GANIL, we propose d(100 MeV)+Be→xn+U as an optimum combination for the production of neutron rich nuclei in the mass region 75≤A≤160. However, the production of tritium gas in the target-converter should be considered carefully. The use of heavier metal targets-converters may cause more severe problems of radioprotection.Our experimental work is closely related to the theoretical investigations. We measure the complete proton spectra for 1.00 and 200 MeV deuteron induced reactions on 8 thin targets (Be, C, Al, Ni, Nb, Ta,, Pb and U) and in the angular region 8 deg C ≤ θp ≤ 120 deg C. The experiments were carried at LNS (Saclay, France) and at NAC (Faure, South Africa). Good quality data (within 10% in absolute value and with 4-8 MeV energy threshold) support our improved LAHET physics modelling for (d,xp) and, consequently, for (d,xn) reactions.Ce travail de thèse se compose d'une partie théorique et d'une partie expérimentale. Nous combinons et utilisons les codes de transport de haute énergie LAHET, de basse énergie MCNP et le code d'activation CINDER. Nos calculs de validation des codes montrent que LAHET néglige la dissociation coulombienne du deutéron. En ajoutant cette contribution, nous obtenons un bon accord avec les données. Nous concluons également que LAHET reproduit bien la production d'isotopes si le modèle de fission ORNL est utilise pour des cibles avec z > 90. Le modèle de fission RAL donne des distributions isotopiques trop larges et ne reproduit pas les données en valeur absolue. Nous examinons différentes combinaisons de faisceaux (projectile, énergie), de cibles de spallation et de cœur de réacteur pour la production de neutrons, l'amplification d'énergie et la production de faisceau radioactif par fission. Nous montrons que les réactions (d, xn) pourraient apporter un certain nombre d'avantages importants, comparées aux réactions (p, xn). Nous concluons que l'utilisation de deutérons au lieu de protons devrait conduire a des intensités de faisceau primaire plus élevées, a un prix réduit du système et a moins de problèmes de radioprotection. Dans le projet SPIRAL Phase-II au GANIL, nous proposons la combinaison d(100 MeV)+Be→xn+U pour une production optimum de noyaux riches en neutron dans la région de masse 75≤A≤160. Cependant, la production de gaz de tritium dans la cible de conversion devrait être soigneusement étudiée. Nous prouvons également que l'utilisation des cibles de conversion de métal plus lourd peut poser des problèmes de radioprotection plus graves. Notre travail expérimental est directement relié aux investigations théoriques. Nous mesurons les distributions en énergie de protons produits par des deutérons de 100 et de 200 MeV sur 8 cibles minces (Be, C, Al, Ni, Nb, Ta, Pb et U) et dans la région angulaire 8° ≤ θp ≤ 120°. Les deux expériences ont été réalisées au LNS (Saclay, france) et au NAC (Faure, Afrique du Sud). Les données de bonne qualité (10% en valeur absolue et un seuil en énergie de 4-8 MeV) sont bien reproduites par le modèle LAHET amélioré pour les réactions (d, xp) et, par conséquent, pour les réaction (d, xn)

State-of-the-art research : reflections on a concerted Nordic-Baltic nuclear energy effort

Quite a few hold the view that nuclear energy will have its renaissance in the not too distant future. Technology is, however, a necessary, but not sufficient condition. The needed prerequisites represent a complex issue. With increasing energy demand and depletion of non-renewable energy resources, nuclear will have to prove its role in an increasing energy mix, globally, regionally and often also nationally. Based on its history, experience with coordinated interplay in electricity production from a variety of energy sources, and science engagements, we argue for a future Nordic/Baltic SHOW CASE: A nuclear weapons free and proliferation safe nuclear energy supplier in the region, with a concerted role in competence building and in international ventures, and with focus on operation, safety economy and societal aspects

FaCE: a tool for Three Body Faddeev calculations with core excitation

FaCE is a self contained programme, with namelist input, that solves the three body Faddeev equations. It enables the inclusion of excitation of one of the three bodies, whilst the other two remain inert. It is particularly useful for obtaining the binding energies and bound state structure compositions of light exotic nuclei treated as three-body systems, given the three effective two body interactions. A large variety of forms for these interactions may be defined, and supersymmetric transformations of these potentials may be calculated whenever two body states need to be removed due to Pauli blocking.Comment: 19 pg, 3 figs, program available for download from ftp://ftp.ph.surrey.ac.uk/pub/thompson/face

EURISOL High Power Targets

Modern Nuclear Physics requires access to higher yields of rare isotopes, that relies on further development of the In-flight and Isotope Separation On-Line (ISOL) production methods. The limits of the In-Flight method will be applied via the next generation facilities FAIR in Germany, RIKEN in Japan and RIBF in the USA. The ISOL method will be explored at facilities including ISAC-TRIUMF in Canada, SPIRAL-2 in France, SPES in Italy, ISOLDE at CERN and eventually at the very ambitious multi-MW EURISOL facility. ISOL and in-flight facilities are complementary entities. While in-flight facilities excel in the production of very short lived radioisotopes independently of their chemical nature, ISOL facilities provide high Radioisotope Beam (RIB) intensities and excellent beam quality for 70 elements. Both production schemes are opening vast and rich fields of nuclear physics research. In this article we will introduce the targets planned for the EURISOL facility and highlight some of the technical and safety challenges that are being addressed. The EURISOL Radioactive Ion Beam production relies on three 100 kW target stations and a 4 MW converter target station, and aims at producing orders of magnitude higher intensities of approximately one thousand different radioisotopes currently available, and to give access to new rare isotopes. As an illustrative example of its potential, beam intensities of the order of 1013 132Sn ions pe r second will be available from EURISOL, providing ideal primary beams for further fragmentation or fusion reactions studies