R. Leroy

Mono 1000: A simple and efficient 2.45 GHz electron cyclotron resonance ion source using a new magnetic structure concept

The production of singly charged atomic and molecular ions with a new 2.45 GHz electron cyclotron resonance ion source has been studied. The ion source Mono 1000 uses a new magnetic confinement structure. The elements Ne, Ar, and Kr are ionized with efficiencies close to 100%, while 45% has been achieved for He. In the case of the molecules SO2 and SF6, more than 90% overall efficiency has been observed with more than 40% of sulfur atoms leaving the source under the form S+. A total extracted yield of 4×1012 singly charged fulleren (C60) ions per second has also been observed.

Ion source developments for RNB production at SPIRAL/GANIL

Abstract The first on-line production system for SPIRAL/GANIL (Radioactive Ion Production System with Acceleration on-Line) phase-I has been commissioned on the SIRa (Radioactive Ion Separator) test bench. Exotic multicharged noble gas ion beams have been obtained during several days. In parallel, a new ECRIS (Electron Cyclotron Resonance Ion Source) for monocharged ions has also been developed. Preliminary off-line results are presented.

The radioactive ion beam production systems for the SPIRAL2 project

The SPIRAL2 project, currently under construction at GANIL, will include an isotope separator on line based facility for the production and acceleration of radioactive ion beams. A superconducting linear accelerator will accelerate 5 mA deuterons up to 40 MeV and 1 mA heavy ions up to 14.5 MeV/u. These primary beams will be used to bombard both thick and thin targets. We are investigating three different techniques to produce the radioactive ion beams: (1) the neutron induced fission of uranium carbide, (2) the direct interaction of deuterons in a uranium carbide target, and (3) the interaction of a heavy ion beam with a target. All these production systems will be coupled to an ion source. Four kinds of ion sources are foreseen for the ionization of the radioactive atoms: an electron cyclotron resonance ion source, a surface ionization ion source, a forced electron beam induced arc discharge ion source, and a laser ion source depending on the characteristics of the desired radioactive ion beam in terms of intensity, efficiency, purity, etc. A presentation of the SPIRAL2 project and of the different production systems is given.

Minimono: An ultracompact permanent magnet ion source for singly charged ions

Minimono is a 2.45 GHz electron cyclotron resonance ion source for singly charged ions which uses only permanent magnets. Measurements of ionization efficiencies, maximum currents extracted, and emittances for H+, 3,4He+, N+, Ne+, Ar+, Kr+, S+, and Si+ were carried out. In the case of buckminster fullerenes, C60+, C602+, and C603+ ions were extracted. The results obtained, the general mechanical simplicity of this ion source, and its low cost make this source attractive for the production of stable and radioactive ions.

High intensity metallic ion beams from an ECR ion source at GANIL

In recent years, progress concerning the production of high intensity of metallic ion beams (58Ni, 48Ca, 76Ge) at GANIL have been performed. The metallic ion from volatile compound method has been successfully used to produce a high intensity nickel beam with the ECR4 ion source: 20 e μA of 58Ni11+ at 24 kV extraction voltage. This beam has been maintained for 8 days and accelerated up to 74.5 MeV/u by our cyclotrons with a mean intensity of 0.13 pμA on target. This high intensity, required for experiment, led to the discovery of the doubly magic 48Ni isotope. The oven method has been first tested with natural metallic calcium on the ECR4 ion source, then used to produce a high power beam (740 W on target, i.e., 0.13 pμA accelerated up to 60 meV/u) of 48Ca still keeping a low consumption (0.09 mg/h). A germanium beam is now under development, using the oven method with germanium oxide. The ionization efficiencies have been measured and compared.

CONSTRAINTS DUE TO THE PRODUCTION OF RADIOACTIVE ION BEAMS IN THE SPIRAL PROJECT

The radioactive ion beams that will be delivered by the SPIRAL facility will be produced by the interaction of a stable high energy (95 MeV/A) and high intensity (2×1013 particle/s) primary ion beam delivered by the GANIL cyclotrons with a carbon target heated to 2000 °C. During this interaction, some radioactive atoms will be created and will diffuse out of the target before entering into an electron cyclotron resonance (ECR) ion source where they will be ionized and extracted. The production of radioactive ion beams with this method implies high radiation fields that activate and can damage materials located in the neighborhood of the target. Therefore, the production system which is composed of the permanent magnet ECR ion source coupled to a graphite target will be changed after two weeks of irradiation. As this ensemble will be very radioactive, this operation has to be supervised by remote control. The radiation levels around the target–ion source system and a detailed description of the different p...

Improvements on metallic ion beams at GANIL with the large-capacity oven

In the last two years the development of the large-capacity oven was continued. First tests on-line with calcium, lead, tin and magnesium beams were achieved. We successfully produced 30μA of Ca9+, 13μA of Pb23+, 8μA of Sn21+, and 50μA of Mg7+. Some deformation of the filament appeared when working at high temperature. Several configurations of the filament and the use of an alternate power supply have been tested to solve this problem. The beam’s intensities and the ionization efficiencies were improved in comparison with the standard microoven performances. The results of magnesium beam, 110μA of Mg5+ obtained with the “MIVOC” method are compared with those using the oven technique.

Combined target-ion source unit for production of rare nuclides

A combined target-ion source unit (ionizing target) has been developed for the on-line production of radioactive single-charged ions. The target is able to withstand temperatures of up to 2500 °C and also acts as an ion source of surface, electron-beam, and laser ionizations. Using tantalum foil as a target material, the on-line combined target-ion source unit efficiency, which is the product of the ionization and release efficiencies, has been obtained for neutron-deficient isotopes of Eu, Gd, and Yb. These nuclides were ionized by the surface ionization inside a hot tungsten target container, holding tantalum foils as a target material. The results of the combined target-ion source unit use for on-line laser resonant ionization spectroscopy investigation of neutron-deficient Gd isotopes have been also presented. For neutron-rich isotopes produced from a high-density UC target, which were ionized by the surface ionization inside the target container, the ionization efficiency values have been obtained close to 100% for Rb and Cs and 10% for In. For Ag and Sn neutron-richisotopes, the values of the electron-beam ionization efficiency in the volume of the targetcontainer, correspondingly equal to 4% and 2%, have been obtained.

Visible light spectrometry measurements for studying an ECRIS plasma and especially applied to the MONO1001 ion source

The cylindrical geometry of the magnetic confinement of the MONO1001 electron cyclotron resonance (ECR) ion source made in GANIL [P. Jardin et al., Rev. Sci. Instrum. 73, 789 (2002)] allows us to measure radial characteristics of the working ECR plasma with helium gas. The physical and the geometrical characteristics of the resonance surface inside the working ECR source have been quantified with the help of a visible light spectrometer. Hence, we have deduced a shape of the electron cyclotron resonance ion sources resonance surface which corresponds closely to our magnetic calculations.

Status report on ECR ion source operation at GANIL

Two electron cyclotron resonance ion sources, ECR 4 and ECR 4 M, provide high charge state beams to the compact cyclotrons, C01 and C02, which are alternative injectors for the GANIL cyclotrons CSS1 and CSS2. When an injector runs for a long period, the off-line source can be used for beam developments or, together with the off-line injector, deliver a beam to a new beam line, called IRRSUD, for atomic physics experiments. Various ions are requested for beam time for periods of 8 to 11 weeks. Although the majority of the required beams comes from gaseous elements, work on the production of beams of metallic ions is always a main activity. New ovens are being developed to improve the capacity and the performances of the standard micro-oven. The latest results with 238U beam, using sputtering method and 76Ge beam using recycling method, are reported here.