Charge breeding at GANIL: Improvements, results, and comparison with the other facilities.

The 1+/n+ method, based on an ECRIS charge breeder (CB) originally developed at the LPSC laboratory, is now implemented at GANIL for the production of Radioactive Ion Beams (RIBs). Prior to its installation in the middle of the low energy beam line of the SPIRAL1 facility, the 1+/n+ system CB has been modified based on the experiments performed on the CARIBU Facility at Argone National Laboratory. Later, it has been tested at the 1+/n+ LPSC test bench to validate its operation performances.

Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion.

Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability.

Erratum: Spectroscopic Quadrupole Moments in ^{96,98}Sr: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60 [Phys. Rev. Lett. 116, 022701 (2016)].

This corrects the article DOI: 10.1103/PhysRevLett.116.

Optimizing charge breeding techniques for ISOL facilities in Europe: Conclusions from the EMILIE project.

The present paper summarizes the results obtained from the past few years in the framework of the Enhanced Multi-Ionization of short-Lived Isotopes for Eurisol (EMILIE) project. The EMILIE project aims at improving the charge breeding techniques with both Electron Cyclotron Resonance Ion Sources (ECRIS) and Electron Beam Ion Sources (EBISs) for European Radioactive Ion Beam (RIB) facilities. Within EMILIE, an original technique for debunching the beam from EBIS charge breeders is being developed, for making an optimal use of the capabilities of CW post-accelerators of the future facilities.

Charge breeder for the SPIRAL1 upgrade: Preliminary results.

In the framework of the SPIRAL1 upgrade under progress at the GANIL lab, the charge breeder based on a LPSC Phoenix ECRIS, first tested at ISOLDE has been modified to benefit of the last enhancements of this device from the 1+/n+ community. The modifications mainly concern the 1 + optics, vacuum techniques, and the RF-buffer gas injection into the charge breeder. Prior to its installation in the midst of the low energy beam line of the SPIRAL1 facility, it has been decided to qualify its performances and several operation modes at the test bench of LPSC lab.

Spectroscopic Quadrupole Moments in {96,98}Sr: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60.

Neutron-rich {96,98}Sr isotopes have been investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross sections. These results allow, for the first time, the drawing of definite conclusions about the shape coexistence of highly deformed prolate and spherical configurations.

Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion.

A special ion trap was initially built up to perform β-ν correlation experiments with radioactive ions. The trap geometry is also well suited to perform experiments with laser-cooled ions, serving for the development of a new type of Penning trap, in the framework of the project TRAPSENSOR at the University of Granada. The goal of this project is to use a single (40)Ca(+) ion as detector for single-ion mass spectrometry.

Ionization efficiency studies with charge breeder and conventional electron cyclotron resonance ion source.

Radioactive Ion Beams play an increasingly important role in several European research facility programs such as SPES, SPIRAL1 Upgrade, and SPIRAL2, but even more for those such as EURISOL. Although remarkable advances of ECRIS charge breeders (CBs) have been achieved, further studies are needed to gain insight on the physics of the charge breeding process. The fundamental plasma processes of charge breeders are studied in the frame of the European collaboration project, EMILIE, for optimizing the charge breeding.

Future carbon beams at SPIRAL1 facility: which method is the most efficient?

Compared to in-flight facilities, Isotope Separator On-Line ones can in principle produce significantly higher radioactive ion beam intensities. On the other hand, they have to cope with delays for the release and ionization which make the production of short-lived isotopes ion beams of reactive and refractory elements particularly difficult. Many efforts are focused on extending the capabilities of ISOL facilities to those challenging beams.

Improved charge breeding efficiency of light ions with an electron cyclotron resonance ion source.

The Californium Rare Isotope Breeder Upgrade is a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS). The facility utilizes a (252)Cf fission source coupled with an electron cyclotron resonance ion source to provide radioactive beam species for the ATLAS experimental program. The californium fission fragment distribution provides nuclei in the mid-mass range which are difficult to extract from production targets using the isotope separation on line technique and are not well populated by low-energy fission of uranium.

First measurement of pure electron shakeoff in the β decay of trapped 6He+ ions.

The electron shakeoff probability of 6Li2+ ions resulting from the β- decay of 6He+ ions has been measured with high precision using a specially designed recoil ion spectrometer. This is the first measurement of a pure electron shakeoff following nuclear β decay, not affected by multielectron processes such as Auger cascades. In this ideal textbook case for the application of the sudden approximation, the experimental ionization probability was found to be P(so)(exp)=0.

Status of the SPIRAL I upgrade at GANIL.

The upgrade of the "Système de Production d'Ions Radioactifs en Ligne" phase I (SPIRAL I) installed at the "Grand Accélérateur National d'Ions Lourds" (GANIL) situated at Caen, France, is in progress and should be ready by 2014. In parallel, the first part of SPIRAL II facility is currently under construction. The global status of the upgrade is presented: goal, radioactive ion production systems, modification of the production cave and impact of the current safety re-evaluation of GANIL.

Prospects for advanced electron cyclotron resonance and electron beam ion source charge breeding methods for EURISOL.

As the most ambitious concept of isotope separation on line (ISOL) facility, EURISOL aims at producing unprecedented intensities of post-accelerated radioactive isotopes. Charge breeding, which transforms the charge state of radioactive beams from 1+ to an n+ charge state prior to post-acceleration, is a key technology which has to overcome the following challenges: high charge states for high energies, efficiency, rapidity and purity. On the roadmap to EURISOL, a dedicated R&D is being undertaken to push forward the frontiers of the present state-of-the-art techniques which use either electron cyclotron resonance or electron beam ion sources.

Development of a surface ionization source for the SPIRAL 2 project.

Development of new radioactive beams, and thus of new target ion sources (TISs) for isotope-separator-on-line production systems are in progress at GANIL for the SPIRAL 2 project. The efficiency and time response measurements of each step in the production process are crucial to predict and maximize the available yields, in particular, for short lived isotopes. This paper presents a method for measuring these quantities that makes use of a stable alkali chopped beam of controlled intensity.

Latest developments at GANIL for stable and radioactive ion beam production.

In the frame of the SPIRAL II (Système de Production d'Ions Radioactifs Accélérés en Ligne Partie II) project, several developments of stable and radioactive ion production systems have been started up. In parallel, GANIL has the ambition to preserve the existing stable and radioactive beams and also to increase its range by offering new ones. In order to identify the best directions for this development, a new group called GANISOL has been formed.

Direct 1+ --> N+ conversion of stable alkali ions using an electron cyclotron resonance ion source.

The 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.

Masses and charge radii of 17-22Ne and the two-proton-halo candidate 17Ne.

High-precision mass and charge radius measurements on ;{17-22}Ne, including the proton-halo candidate 17Ne, have been performed with Penning trap mass spectrometry and collinear laser spectroscopy. The 17Ne mass uncertainty is improved by factor 50, and the charge radii of ;{17-19}Ne are determined for the first time. The fermionic molecular dynamics model explains the pronounced changes in the ground-state structure.

Restoration of the n=82 shell gap from direct mass measurements of 132,134Sn.

A high-precision direct Penning trap mass measurement has revealed a 0.5-MeV deviation of the binding energy of (134)Sn from the currently accepted value. The corrected mass assignment of this neutron-rich nuclide restores the neutron-shell gap at N=82, previously considered to be a case of "shell quenching.

Status of the PHOENIX electron cyclotron resonance charge breeder at ISOLDE, CERN.

We report here on the last progresses made with the PHOENIX electron cyclotron resonance charge breeder test bench at ISOLDE. Recently, an experiment was performed to test the trapping of (61)Fe daughter nuclides from the decay of (61)Mn nuclides. Preliminary results are given.

Coulomb excitation of neutron-rich Zn isotopes: first observation of the 2(1)+ state in 80Zn.

Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 2(1)+ state in 78Zn could be firmly established and for the first time the 2+ --> 0(1)+ transition in 80Zn was observed at 1492(1) keV. B(E2,2(1)+ --> 0(1)+) values were extracted for (74,76,78,80)Zn and compared to large scale shell model calculations.

Coulomb excitation of 68,70Cu: first use of postaccelerated isomeric beams.

We report on the first low-energy Coulomb excitation measurements with radioactive Ipi=6- beams of odd-odd nuclei 68,70Cu. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2.83 MeV/nucleon.

Measurement of the sign of the spectroscopic quadrupole moment for the 2(1)+ state in 70Se: no evidence for oblate shape.

Using a method whereby molecular and atomic ions are independently selected, an isobarically pure beam of 70Se ions was postaccelerated to an energy of 206 MeV using REX-ISOLDE. Coulomb-excitation yields for states in the beam and target nuclei were deduced by recording deexcitation gamma rays in the highly segmented MINIBALL gamma-ray spectrometer in coincidence with scattered particles in a silicon detector. At these energies, the Coulomb-excitation yield for the first 2+ state is expected to be strongly sensitive to the sign of the spectroscopic quadrupole moment through the nuclear reorientation effect.

"Safe" Coulomb excitation of 30Mg.

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed.