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

A new cross section measurement of reactions induced by 3He-particles on a carbon target

International audienceThe production of intense beams of light radioactive nuclei can be achieved at the SPIRAL2 facility using intense stable beams accelerated by the driver accelerator and impinging on light targets. The isotope 14O is identied to be of high interest for future experiments. The excitation function of the production reaction 12C(3He, n)14O was measured between 7 and 35 MeV. Results are compared with literature data. As an additional result, we report the rst cross-section measurement for the 12C(3He, +n)10C reaction. Based on this new result, the potential in-target 14O yield at SPIRAL2 was estimated: 2.4x1011 pps, for 1 mA of 3He at 35 MeV. This is a factor 140 higher than the in-target yield at SPIRAL1

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

New pathway to bypass the 15O waiting point

We propose the sequential reaction process $^{15}$O($p$,$\gamma)(\beta^{+}$)$^{16}$O as a new pathway to bypass of the $^{15}$O waiting point. This exotic reaction is found to have a surprisingly high cross section, approximately 10$^{10}$ times higher than the $^{15}$O($p$,$\beta^{+}$)$^{16}$O. These cross sections were calculated after precise measurements of energies and widths of the proton-unbound $^{16}$F low lying states, obtained using the H($^{15}$O,p)$^{15}$O reaction. The large $(p,\gamma)(\beta^{+})$ cross section can be understood to arise from the more efficient feeding of the low energy wing of the ground state resonance by the gamma decay. The implications of the new reaction in novae explosions and X-ray bursts are discussed.Comment: submitte

One-neutron removal reactions on neutron-rich psd-shell nuclei

A systematic study of high energy, one-neutron removal reactions on 23 neutron-rich, psd--shell nuclei (Z=5-9, A=12-25) has been carried out. The longitudinal momentum distributions of the core fragments and corresponding single-neutron removal cross sections are reported for reactions on a carbon target. Extended Glauber model calculations, weighted by the spectroscopic factors obtained from shell model calculations, are compared to the experimental results. Conclusions are drawn regarding the use of such reactions as a spectroscopic tool and spin-parity assignments are proposed for 15B, 17C, 19-21N, 21,23O, 23-25F. The nature of the weakly bound systems 14B and 15,17C is discussed.Comment: 11 pages + 2 figure

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

Elements Discrimination in the Study of Super-Heavy Elements using an Ionization Chamber

Dedicated ionization chamber was built and installed to measure the energy loss of very heavy nuclei at 2.7 MeV/u produced in fusion reactions in inverse kinematics (beam of 208Pb). After going through the ionization chamber, products of reactions on 12C, 18O targets are implanted in a Si detector. Their identification through their alpha decay chain is ambiguous when their half-life is short. After calibration with Pb and Th nuclei, the ionization chamber signal allowed us to resolve these ambiguities. In the search for rare super-heavy nuclei produced in fusion reactions in inverse or symmetric kinematics, such a chamber will provide direct information on the nuclear charge of each implanted nucleus.Comment: submitted to NIMA, 10 pages+4 figures, Latex, uses elsart.cls and grahpic

Production of multi-charged phosphorus ions with ecris 'SUPERSHyPIE' at GANIL

The Ganil's Ion Production Group tested the source SUPERSHyPIE123 for theproduction of phosphorus n+ ion beams. The SUPERSHyPIE ecris is used for many testsof multi-charged ion production and supply ion beams for LIMBE4 (low energie beamline). This ion source works with a 14.5ghz RF power injected by a circular waveguide inthe axis of the sourc

Search for Superscreening effect in Superconductor

4 pages, 3 figures, Expérience au GANIL avec SPIRAL/EXOGAMThe decay of $^{19}$O($\beta^-$) and $^{19}$Ne($\beta^+$) implanted in niobium in its superconducting and metallic phase was measured using purified radioactive beams produced by the SPIRAL/GANIL facility. Half-lives and branching ratios measured in the two phases are consistent within one-sigma error bar. This measurement casts strong doubts on the predicted strong electron screening in superconductor, the so-called superscreening. The measured difference in screening potential energy is 110(90) eV for $^{19}$Ne and 400(320) eV for $^{19}$O. Precise determinations of the half-lives were obtained for $^{19}$O: 26.476(9)~s and $^{19}$Ne: 17.254(5)~s

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

International audienceThe cylindrical geometry of the magnetic confinement of the MONO1001 ECR ion sourcemade in GANIL1, allows us to measure radial characteristics of the working ECR plasmawith Helium gas. The physical and the geometrical characteristics of the resonance surfaceinside the working ECR source have been quantified with the help of a visible lightspectrometer. Hence, we have deduced a shape of the ECRIS resonance surface whichcorresponds closely to our magnetic calculations