Method for Efficiency and Time Response Measurement on Diverse Target Ion Sources with Stable Alkali

International audienceDevelopments of new setups for radioactive ion beam production by the isotope-separator-on-line (ISOL) method are underway at GANIL in the frame of the SPIRAL (Système de Production d'Ions Radioactifs Accélérés en Ligne) and SPIRAL-II projects. The measurement of total efficiency and time behaviour of these new target/ion-source systems (TISSs) is a crucial step for these devices which aims to produce short-lived isotopes with high intensity. The overall atom-to-ion transformation efficiency depends on several processes: diffusion of the atoms out of the production target, effusion towards the ion source and ionization. The efficiency can be extracted using the ratio between the emerging yield and implanted flux in the TISS. Several methods have already been developed to achieve these measurements: the use of stable or radioactive beams, gas injection, or the introduction of solid material into the TISS. This paper focuses primarily on a method that uses stable alkali. A pulsed/CW alkali ion gun has been built and will be used to optimise diverse TISSs

Permanent magnets under irradiation and radiocative alkali ion beam development for SPIRAL1

International audienceUp to now, eighteen Target Ion Source Systems (TISSs) have been built and used for the production of radioactive ion beams on SPIRAL 1 facility, based on the Isotope- Separator-On-Line (ISOL) method. The TISSs are composed of thick carbon targets and of fully permanentmagnet Electron Cyclotron Resonance Ion Sources (ECRISs) of the Nanogan III type. After irradiation and a decay period of two years, the irradiated TISSs are dismounted and if their magnetic fields are still suitable, the ECRIS are used with a new target. Thereby thirty-two runs have been performed using new or renewed TISSs. , After irradiation, the measured magnetic field sometimes reveals magnet damage. Our experience is reported here. In the second section, we present the progress on the NanoNaKE setup, which aims to extend the radioactive ion beams in SPIRAL 1 to the alkali elements, by connecting a surface-ionization source to the Nanogan III ECRIS via a compact 1+ ion beam line. The main issues and difficulties are discussed and the preliminary solutions are described

Study of 124^{124}Sn+136^{136}Xe fusion-evaporation: analysis of a rare-event experiment

7 pages, 4 figuresFusion-evaporation in the $^{124}$Sn+$^{136}$Xe system is studied using a high intensity xenon beam provided by the Ganil accelerator and the LISE3 wien filter for the selection of the products. Due to the mass symmetry of the entrance system, the rejection of the beam by the spectrometer was of the order of $5times10^8$. We have thus performed a detailed statistical analysis to estimate random events and to infer the fusion-evaporation cross sections. No signicant decay events were detected and upper limit cross sections of 172~pb, 87~pb and 235~pb were deduced for the synthesis of $^{257}$Rf, $^{258}$Rf and $^{259}$Rf, respectively

Spectroscopy of the unbound nucleus 18Na

Expérience GANIL, SPIRALInternational audienceThe unbound nucleus 18Na, the intermediate nucleus in the two-proton radioactivity of 19Mg, is studied through the resonant elastic scattering 17Ne(p,17Ne)p. The spectroscopic information obtained in this experiment is discussed and put in perspective with previous measurements and the structure of the mirror nucleus 18N

Production of radioactive alkali multi–charged ions at GANIL: Problems and possible solutions

International audienc

Direct 1+ →\rightarrow N+ conversion of stable alkali ions using an electron cyclotron resonance ion source

International audienceThe production of radioactive ions using the Isotope Separation On-Line method gives rise, in most cases, to singly charged ions. In order to perform experiments with postaccelerated radioactive ion beams, these ions have to be multicharged. We describe here a new compact design for a charge breeder that will be coupled to the production target of SPIRAL1 at GANIL. We present recent results obtained offline with stable alkali ions Na, K, Rb, and Cs on the SIRa test bench. Particularly, 1+ to N+ conversion efficiencies and conversion times are presented. Several points have been identified for the improvements of the present performances

NanoNaKe : production of alkali ion beams for SPIRAL1/GANIL

International audienceThe SPIRAL1 facility is delivering radioactive ion beams at GANIL since 2001. However, the present operation is limited to gaseous elements (noble gases, oxygen, nitrogen...). The aim of the NanoNaKe project is to enlarge the available radioactive beams to alkali elements (especially Na and K) by using a new Target-Ion Source system for SPIRAL1. In this setup, a 1+ surface ionization ion source is directly coupled to the present Nanogan3 ECRIS which is used as a charge breeder. The advantage of such a compact geometry is that only minor modifications of the SPIRAL1 production cave are needed. The first part of the system (target-surface ionization ion source: MonoNaKe) has already been tested and validated online in 2007 for the production of different isotopes of Li+, Na+ and K+ [1]. Furthermore, a first demonstration of the principle of coupling Mononake to Nanogan3 was experimentally obtained with 47K5+ ions [2]. In order to increase the performances of Nanonake, the charge breeding of 1+ ions into the ECRIS has been successfully tested off-line using different stable alkali ions (Na+, K+, Rb+ and Cs+) on the SIRA test-bench. Significantly improved charge breeding efficiencies have been measured and some limitations in the performances of the present device have also been identified. An upgraded version of the setup will be tested on-line on SIRA in May 2009 for the production of multicharged radioactive alkali ions. Depending on the results of this experiment, a Target-Ion Source using Nanonake could possibly be installed on SPIRAL1 before 2012 for a physics experiment. A complete description of the setup as well as off-line and on-line results will be presented

Development of a 1+/N+ setup for the production of multicharged radioactive alkali ions in SPIRAL

International audienceIn the framework of the production of radioactive ion beams by the isotope separator online method, a new system has been developed at GANIL/SPIRAL I to produce multicharged alkali ions. The principle, referred to as the “direct 1+/N+ method,” consists of a surface ionization source associated with a multicharged electron-cyclotron-resonance ion source without an intermediate mass separator. This new system has been tested online using a 48Ca primary beam at 60.3 A MeV. The experimental evidence of the direct 1+/N+ process has been obtained for a potential difference between the two sources of 11 V and with a 1+/N+ charge breeding efficiency of 0.04% for 47K5+. This value is significantly lower than the value of 6% obtained for stable K ions with the standard 1+/N+ method. A possible explanation is given in the text

Development of a 1+ /N+ setup for the production of multicharged radioactive alkali ions in SPIRAL

In the framework of the production of radioactive ion beams by the isotope separator online method, a new system has been developed at GANIL/SPIRAL I to produce multicharged alkali ions. The principle, referred to as the “direct 1 + /N+ method,” consists of a surface ionization source associated with a multicharged electron-cyclotron-resonance ion source without an intermediate mass separator. This new system has been tested online using a 48Ca primary beam at 60.3 A MeV. The experimental evidence of the direct 1 + /N+ process has been obtained for a potential difference between the two sources of 11 V and with a 1 + /N+ charge breeding efficiency of 0.04% for 47K5+. This value is significantly lower than the value of 6% obtained for stable K ions with the standard 1 + /N+ method. A possible explanation is given in the text

Development of a surface ionization source for the production of radioactive alkali ions in SPIRAL

International audienceIn the framework of the production of radioactive alkali ion beams by the isotope separator on-line (ISOL) method in SPIRAL, a surface ionization source has been developed at GANIL to produce singly-charged ions of Li, Na and K. This new source has been designed to work in the hostile environment found at SPIRAL whilst having a long lifetime. This new system of production has two ohmic heating components: the first for the target oven and the second for the ionizer. The latter, being in carbon, offers high reliability and competitive ionisation efficiency. This new surface ionization source has been tested on line using a 48Ca primary beam at 60,3A MeV with an intensity of 0,14 pµA. The ionization efficiencies obtained for Li, Na and K are significantly better than the theoretical values calculated using the known Langmuir surface ionisation equation. Moreover, the design of the ion source avoids the cavity effects reported by Kirchner. The enhanced efficiency can be understood by considering a particular effect related to the polarization of the ionizer. This feature is shown to be extremely important also for short-lived isotopes. In the future, this source will be associated with the multicharged electron-cyclotron-resonance (ECR) ion source NANOGAN III for production of multicharged alkali ions in SPIRAL. The preliminary tests of the setup for the production of multicharged alkali ions will also be presented in this contribution