https://link.springer.com/content/pdf/10.1007%2Fs13361-017-1617-z.pdf

Isobar Separation in a Multiple-Reflection Time-of-Flight Mass Spectrometer by Mass-Selective Re-Trapping.

Nuclear Data Sheets for A=23

Since 2001, the SPIRAL 1 facility has been one of the pioneering facilities in ISOL techniques for re-accelerating radioactive ion beams: the fragmentation of the heavy ion beams of GANIL on graphite targets and subsequent ionization in the Nanogan ECR ion source has permitted to deliver beams of gaseous elements (He, N, O, F, Ne, Ar, Kr) to numerous experiments. Thanks to the CIME cyclotron, energies up to 20 AMeV could be obtained. In 2014, the facility was stopped to undertake a major upgrade, with the aim to extend the production capabilities of SPIRAL 1 to a number of new elements. This upgrade, which is presently under commissioning, consists in the integration of an ECR booster in the SPIRAL 1 beam line to charge breed the beam of different 1+ sources. A FEBIAD source (the so-called VADIS from ISOLDE) was chosen to be the future workhorse for producing many metallic ion beams. This source was coupled to the SPIRAL 1 graphite targets and tested on-line with different beams at GANIL. The charge breeder is an upgraded version of the Phoenix booster which was previously tested in ISOLDE. It was recently commissioned at LPSC and lately in the SPIRAL 1 beam lines with stable beams. The upgrade additionally permits the use of other target material than graphite. In particular, the use of fragmentation targets will permit to produce higher intensities than from projectile fragmentation, and thin targets of high Z will be used for producing beams by fusion-evaporation. The performances of the aforementioned ingredients of the upgrade (targets, 1+ source and charge breeder) have been and are still being optimized in the frame of different European projects (EMILIE, ENSAR and ENSAR2). The upgraded SPIRAL 1 facility will provide soon its first new beams for physics and further beam development are undertaken to prepare for the next AGATA campaign. The results obtained during the on-line commissioning period permit to evaluate intensities for new beams from the upgraded facility. © 2001 Elsevier Science. All rights reserved.

New exotic beams from the SPIRAL 1 upgrade

Mass measurements give us the nuclear binding energy, a fundamental property that is indispensable for the study of nuclear structure, stellar nucleosynthesis and neutron-star composition, as well as atomic and weak-interaction physics. The dedicated experimental programs at all major nuclear-physics installations on the planet is excellent testimony to their relevance. The use of stored ions (in rings and traps) has made an enormous impact on the field of mass spectrometry. While Penning traps contribute particularly with their hallmark precision, another type of ion trap has now come into play: the multi-reflection time-of-flight mass spectrometer (MR-TOF MS). Read on for a tour of mass-measurement installations at radioactive-beam facilities worldwide with the physics highlights achieved since the last TCP conference.

New mass measurements with trapped (radioactive) ions and related fundamental physics

The new generation of nuclear facilities calls for new technological developments to produce,
accelerate, manipulate and analyse exotic nuclei. The main topic of this thesis work was the
simulation, design and test of a Multi-Reflection Time-of-Flight Mass spectrometer (MR-ToFMS)
for fast mass separation and fast mass measurement of radioactive ions in the installations S3
and DESIR at SPIRAL2. Such a device could separate isobaric nuclei and provide SPIRAL2 with
high purity beams. Also, its mass measurement capabilities would help to determine binding
energies of exotic and superheavy nuclei with a high precision. This apparatus has been simulated
with the SIMION 8.1 software and designed accordingly. First offline tests have been performed
with a stable ion source at LPC Caen. In addition a low-aberration electrostatic deflector has been
simulated and designed to operate with this MR-ToF-MS without spoiling its performances. This
work also describes the analysis and results of the first online tests of a FEBIAD-type ion source
intended to provide SPIRAL1 and SPIRAL2 radioactive beams of competitive intensities. Finally,
we describe the analysis of a nuclear physics experiment, including the calibration of the different
detectors and the gamma-spectroscopy of nuclei in the vicinity of the doubly magic 100Sn.

Design, simulations and test of a Time-of-Flight spectrometer for mass measurement of exotic beams from SPIRAL1/SPIRAL2 and γ-ray spectroscopy of N=Z nuclei close to $^{100}$Sn

The DESIR (decay, excitation and storage of radioactive ions) facility at GANIL-SPIRAL2 will receive a large variety of exotic nuclei at low energy (up to 60 keV) with high intensities. However, the production methods of radioactive beams are non selective, limiting the purity of the beams of interest. Moreover, the high precision needed for nuclear structure and astrophysics studies using beta decay spectroscopy, laser spectroscopy and trap-based experiments at DESIR requires highly pure samples of exotic nuclei. The aim of the double-Pennig-trap mass separator PIPERADE is to deliver large and very pure samples of exotic nuclei to the different experiments in DESIR. New excitation schemes and a large inner diameter of the first trap will mitigate space charge effects to attempt trapping of up to 105 ions per pulse. The purification cycle will be performed in a few milliseconds so that short-lived nuclei can be purified. To extract the nuclides of interest from the large amount of isobaric contaminants, a resolving power of 105 is mandatory. Afterwards the ions of interest will be accumulated in the second trap until they constitute a sufficiently pure sample for the measurements. The status of the project is presented.

Conception of PIPERADE: A high-capacity Penning-trap mass separator for high isobaric contamination at DESIR

Half-lives and branching ratios for the two mirror $ \beta$ decays of$^{23}$Mg and$^{27}$Si have been measured at the University of Jyvaskyla with the IGISOL facility. The results obtained, $ T_{1/2}=11.303(3)$ s and $ T_{1/2}= 4.112(2)$ s for the half-lives of$^{23}$Mg and$^{27}$Si , respectively, are 7 and 8 times more precise than the averages of previous measurements. The values obtained for the super-allowed branching ratios of$^{23}$Mg and$^{27}$Si are $ B.R.=92.18(8)\%$ and $ B.R.=99.74(2)\%$ , respectively. The result for$^{23}$Mg is three times more precise than the average of the previous measurements, while for$^{27}$Si the precision has not been improved, the average of the previous measurements being already very precise. Isospin-symmetry-breaking corrections have been calculated for the two nuclei to determine the corrected $ {F}t$ value.

/pdf/precise-measurements-of-half-lives-and-branching-ratios-for-44fnctb21a.pdf

Precise measurements of half-lives and branching ratios for the $ \beta$ mirror transitions in the decay of $^{23}$Mg and $^{27}$Si

A double Penning trap is being commissioned at CENBG Bordeaux for the future DESIR/SPIRAL2 facility of GANIL. The setup is designed to perform both high-resolution mass separation of the ion beam for trap-assisted spectroscopy, and high-accuracy mass spectrometry of short-lived nuclides. In this paper, the technical details of the new device are described. First offline tests with the purification trap are also presented, showing a mass resolving power of about 10 5 .

B. Thomas

Papers

Conception of PIPERADE: A high-capacity Penning-trap mass separator for high isobaric contamination at DESIR

Precise measurements of half-lives and branching ratios for the $ \beta$ mirror transitions in the decay of $^{23}$Mg and $^{27}$Si

PIPERADE: A double Penning trap for mass separation and mass spectrometry at DESIR/SPIRAL2