The ALTO project at IPN Orsay

In order to probe neutron rich radioactive noble gases produced by photo-fission, a PARRNe1 experiment (Production d'Atomes Radioactifs Riches en Neutrons) has been carried out at CERN. The incident electron beam of 50 MeV was delivered by the LIL machine: LEP Injector Linac. The experiment allowed to compare under the same conditions two production methods of radioactive noble gases: fission induced by fast neutrons and photo-fission. The obtained results show that the use of the electrons is a promising mode to get intense neutron rich ion beams. Thereafter, the success of this photo-fission experiment, a conceptual design for the installation at IPN Orsay of a 50 MeV electron accelerator close to the PARRNe-2 device has been worked out: ALTO Project. This work has started within a collaboration between IPNO, LAL and CERN groups.Comment: 14 pages, pdf file, International School-Seminar on Heavy-Ion Physics 7 (2002

Modeling the bremsstrahlung emission from converters

The bremsstrahlung angular and energy theoretical distributions delivered from W and UCx thick converters are reported. This study is focussed on initial kinetic energies of the electron beam included in the range 30-60 MeV, suitable for the production of large radiative yields able to induce the $^{238}$U fission. These results offer the possibility to evaluate the required shielding for a neutron rich nuclei source

METALLIC ION DEVELOPMENTS AT GANIL

Radioactive ion beams (RIB) are routinely produced at GANIL by fragmentation of the projectile. A possible way to improve the RIB intensity is to increase the primary beam intensity impinging the target. Although high intensities can be obtained with an ECR ion source for gaseous elements, it is more difficult for metallic elements due to the poor ionization efficiency of the source. This report deals with metallic ion beam production at high intensity. Experimental results for Ca, Ni and Fe are presented. The oven and the MIVOC methods are compared

How to obtain lattices from (f,σ,δ)-codes via a generalization of Construction A

We show how cyclic (f,σ,δ)-codes over finite rings canonically induce a Z-lattice in RN by using certain quotients of orders in nonassociative division algebras defined using the skew polynomial f. This construction generalizes the one using certain σ-constacyclic codes by Ducoat and Oggier, which used quotients of orders in non-commutative associative division algebras defined by f, and can be viewed as a generalization of the classical Construction A for lattices from linear codes. It has the potential to be applied to coset coding, in particular to wire-tap coding. Previous results by Ducoat and Oggier are obtained as special cases

Développement d'un système d'identification pour SPIRAL et test d'une cible d'uranium liquide dans le cadre du projet PARRNe

In its first part, this research thesis addresses an important issue of the SPIRAL project: the study and realisation of a system of identification of radioactive beams at low energy. The objective is to characterise without any ambiguity radioactive beams emitted by the target-source set. The identification method is based on radioactive decays. After a descriptive presentation of radioactive beams and of their production mode, the author presents the GANIL laboratory and the SPIRAL project. This project is described in terms of beam production, identification, acceleration and control. The author then presents the different methods of measurement of the intensity of radioactive beams, and justifies the choice of the decay-based measurement method. He gives a general presentation of the identification system with a description of equipment used for the detection: germanium-, plastic-, and silicon-based sensors, and a tape drive. Different identification modes are also presented. In the next part, the author presents the general system operation structure: command and control of the detection equipment, acquisition, identification server, graphic interface. The last part presents the research and development program implemented in Orsay to produce neutron-rich radioactive ion beams. Some experiments of the PARRNe project are analysed and described, notably one which is based on a first time use of a liquid uranium target under beamCe travail de thèse traite, dans une première partie, un point important du projet SPIRAL : l'étude et la réalisation d'un système d'identification des faisceaux radioactifs à basse énergie. Il s'agit de caractériser sans ambiguïté les faisceaux radioactifs issus de l'ensemble cible-source de production. la méthode d'identification utilise les décroissances radioactives. Ce système, répondant à un cahier des charges bien déterminé, est automatisé et doit permettre une utilisation par un non-spécialiste. Ce travail de thèse présente la description et les résultats du test en ligne d’une cible d'uranium liquide dans le cadre du programme PARRNe. Le premier chapitre, après une introduction descriptive des faisceaux radioactifs et de leur mode de production, présente le laboratoire GANIL et le projet SPIRAL. Le deuxième chapitre présente les différentes méthodes d mesure de l’intensité des faisceaux radioactifs et justifie le choix de la méthode de mesure par décroissance.Le troisième chapitre donne une présentation générale du système d'identification avec une description des équipements utilisés pour la détection : détecteurs germanium, plastique, silicium et le dérouleur de la bande.Le quatrième chapitre explicite la structure générale du fonctionnement du système.Le cinquième chapitre présente le programme le programme de recherche et développement mené à l'IPN Orsay pour produire des faisceaux d'ions radioactifs riches en neutrons. La conclusion rappelle les principaux résultats de ce travail et présente les perspectives d'amélioration et de développement envisagées

Exploratory analysis of a neutron-rich nuclei source based on photo-fission

A source of neutron rich ions can be conceived through the photo-fission process. An exploratory study of such a source is realized. A survey of the radiative electron energy loss theory is reported in order to estimate numerically the bremsstrahlung production of thick targets. The resulted bremsstrahlung angular and energy theoretical distributions delivered from W and UCx thick converters are presented and compared with previous results. Some quantities as the number of fission events produced in the fissionable source and the energy loss in the converters are also reported as function of the geometry of the combination and the incident electron energy. An attempt of comparison with experimental data shows a quantitative agreement. This study is focussed on initial kinetic energies of the electron beam included in the range 30-60 MeV, suitable for the production of large radiative gamma-ray yields able to induce the $^{238}$U fission through the giant dipole resonance. A confrontation with the number of fission events produced in the frame of the fast neutron induced fission method indicates that the photo-fission can be a competitive concept