Production d'ions alcalins radioactifs

http://polywww.in2p3.fr/jrjc2005National audienceDans le domaine de la physique nucléaire, l’intérêt pour les noyaux qui sont loin de la vallée de la stabilité stimule la recherche et le développement de faisceaux radioactifs. Notre étude porte plus particulièrement sur la production de faisceau d'ions 21Na, car il permet d'étudier le passage de cycle C, N, O vers des cycles plus rapides dans les étoiles et de faisceau d'ions 11Li car sa structure est encore mal comprise

ECR Ion sources for radioactive ion beam production

17th workshop on ECR Ion Sources and their Applications, Lanzhou, Chine (2006)International audienceECRIS's dedicated to radioactive ion producton must be as efficient as those used for production of stable elements, but in addition they are subject to more specific constraints such as radiation hardness, short atom-to-ion transformation time, beam purity and low cost. Up to now, different target/ion-source system (TISSs) have been designed, using singly-charged ECRISs, multi-charged ion sources or an association of singly-to-multi-charged ECRISs. The main goal, constraints and advantages of different existing ECR setups wil be compared before a more detailed description is given of the one designed for the SPIRAL II project and ist future improvements

Nuclear charge radius of 8^8He

The root-mean-square (rms) nuclear charge radius of ^8He, the most neutron-rich of all particle-stable nuclei, has been determined for the first time to be 1.93(3) fm. In addition, the rms charge radius of ^6He was measured to be 2.068(11) fm, in excellent agreement with a previous result. The significant reduction in charge radius from ^6He to ^8He is an indication of the change in the correlations of the excess neutrons and is consistent with the ^8He neutron halo structure. The experiment was based on laser spectroscopy of individual helium atoms cooled and confined in a magneto-optical trap. Charge radii were extracted from the measured isotope shifts with the help of precision atomic theory calculations

Recherche et développement concernant la production d'ions radioactifs dans le cadre de SPIRAL

This thesis is related to the R&D for the production of radioactive ion beams by the ISOL method for SPIRAL at GANIL. Two studies concerning improvements to the performance of SPIRAL target-source system have been made, using a statistical approach to the atoms-to-ions transformation. The first study concerns the transformation time between the production of the radioactive atoms of $^{35}$Ar inside a target and the extraction of the radioactive ions from the source with the TARGISOL set-up (target + ECR source). The goal was to determine the diffusion coefficients of the Ar for the carbon target. The results were presented and illustrate the difficulty of this work. The second study is the application of the statistical approach to the surface ionization source. It allowed one to define and to build a new MonoNaKe set-up for the production of 1+ radioactive alkaline ions. Radioactive ions of $^{37,47}$K, $^{25,26,27,28,30}$Na, $^{8,9}$Li and $^{28,29,30,31}$Al were produced.For the production of the multicharged radioactive alkali ions, the MonoNaKe target/ion-source system was coupled to the ECR source of SPIRAL 1 without a mass separator (1+/N+ direct method). A first radioactive ion beam of $^{47}$K$^{5+}$ was extracted at the SIRa test bench.A surface ionization test source based on the same technical characteristics of MonoNaKe has been built. The goal of this system will be to define a prototype of source adapted to the constraints of SPIRAL 2 (ionization efficiency and lifetime).Ce travail de thèse concerne l'étude de la production de faisceaux d'ions radioactifs par la méthode ISOL. Il s'inscrit dans le cadre de la R&D pour SPIRAL à GANIL. Deux études destinées à améliorer les performances de SPIRAL ont été réalisées à partir d'une approche statistique originale du processus de transformation atomes-ions.La première étude porte sur les temps de transformation entre les instants de production des atomes radioactifs d'$^{35}$Ar dans une cible et d'extraction des ions radioactifs correspondant hors de la source à l'aide du dispositif TARGISOL (cible + source ECR). Le but était de déterminer les coefficients de diffusion de l'Ar dans des cibles en carbone graphite. Les résultats sont présentés et démontrent la rigueur qu'exige cette étude.La seconde étude est une application de l'approche statistique au fonctionnement d'une source à ionisation de surface. Elle a permis de redéfinir et de construire un ensemble de production de faisceaux d'ions 1+ alcalins radioactifs MonoNaKe. Des ions radioactifs de $^{37,47}$K, $^{25,26,27,28,30}$Na, $^{8,9}$Li et $^{28,29,30,31}Al ont été produits.Pour produire un faisceau d'ions alcalins radioactifs multichargés, l'ensemble cible-source MonoNaKe a été couplé avec une source ECR de même type que celle utilisée actuellement sur SPIRAL 1, sans utiliser de séparateur de masse (méthode 1+/N+ directe). Un premier faisceau d'ions radioactifs$^{47}$K$^{5+}$ a été extrait sur le banc de test SIRa.Une source de test hors ligne basée sur les mêmes principes que ceux adoptés pour la définition de MonoNaKe a été construite. Son but est d'élaborer un prototype de source répondant aux contraintes de SPIRAL 2 (efficacité d'ionisation et durée de vie)

SPIRAL at GANIL: Latest Results and Plans for the Future

International audienceThe first accelerated exotic beam of the SPIRAL (Production System of Radioactive Ion and Acceleration On-Line) facility at GANIL at Caen has been delivered for experiments in September 2001. After working for almost 5 years, 32 experiments were performed in the facility using exotic isotopes of helium, oxygen, neon, argon and krypton. The intensities of the radioactive beams increased since the first beam was delivered. Nominal intensity values are achieved for most of noble gas beams. Developments of new beams as well as the increasing of present intensities for a number of isotopes are being undertaken. In particular, in this contribution it is presented the first results obtained for the production of light alkali beams. Other developments are also envisaged in the close future

Production of high intensity primary beams at GANIL

International audienceThe 100 kV platform used for the production of primary beams has been modified in order to increase the beam intensity. The configuration of the new platform is described and preliminary results are reported. A gain intensity of a factor of 2 has already been obtained for sulfur: $^{36}$S (65% enriched) 3.2 kW at 77.5 MeV/u, i.e., 1.14 p$\mu$A, as well as for nickel: $^{58}$Ni (68%) 1.5 kW at 74.5 MeV/uA, i.e., 0.35 p$\mu$A

Direct 1+1^+ to n+n^+ method for production of radioactive alkaline ions

International audienceIn the frame of the production of radioactive ion beams by isotope separator on line method, a new principle of target/ion-source system has been developed at GANIL to produce multicharged ions of alkalis. The principle consists of a surface ionization source associated to a multicharged electron-cyclotron-resonance ion source (ECRIS) named NANOGAN III [R. Leroy et al., AIP Conf. Proc. 749, 137 (2004)] presently used to produce radioactive ions of gas on Système de Production d'Ions Radioactifs Accélérés en Ligne partie I. The singly charged ions are injected in the multicharged ion source without mass separation, through a very short beam line including several stages of acceleration, focusing, deceleration, and rf injection. The first tests showed a good behavior of the ECRIS with the new rf coupling. A study of the surface ionization source is in progress in order to improve its coupling to the $1^+$ beam line

Set-up for systematic measurements of diffusion of atoms from ISOL targets

International audienceThe design of radioactive ion production systems by Isotope Separator On Line method requires knowledge of diffusion features of atoms out of solids. With respect to the large number of possible diffusing atoms in target material, it is often difficult to find the right information in the literature, and inter-comparisons are often difficult due to differences in the experimental techniques and conditions. The TARGISOL European collaboration has the aim to study the relevant variables governing the release of radioactive elements from targets, to produce new radioactive ion beams and to build a data base which can facilitate the design of radioactive ion beam setups. The role of GANIL in this collaboration is to develop and produce new radioactive beams and provide new diffusion coefficient data. For this purpose, GANIL has designed a new system which removes part of the problems of comparing data. The approach is systematic measurements of release properties from several targets using the same process, the same apparatus and during the same experiment. This new approach will be presented with the set-up and the characterizing tests of the apparatus. Results of two experimental periods will be presented at this conferenc

Status report of stable and radioactive ion beam production at GANIL

International audienceGANIL has been producing many stable and radioactive ion beams for nearly 25 years. Constant progresses have been made in terms of intensity, stability, and reliability. The intensity for some stable metallic beams now exceeds or approaches the p µA level at an energy up to 95 MeV/u, e.g., 1.14 p µA for 36S (65% enriched) at 77 MeV/u, 0.35 p µA for 58Ni (63% enriched) at 74 MeV/u. Some recent results with Magnesocene using the metallic ions from volatile compounds method should also make possible the production of metallic beams with an intensity greater than 1 p µA. This has still to be measured. The ISOL facility SPIRAL I has been in operation for almost six years. Up to now, 17 exotic He experiments have been done with 14 target/ion-source (TIS) units; 19 other experiments (with O, Ne, Ar, and Kr) have been achieved with 14 TISs. Statistics show a fairly good ratio of available beam time to scheduled beam time. The radioactive beams and available intensities are compiled in this report. Future developments on radioactive ion beam production are briefly presented, while more details will be discussed elsewhere at this conference