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

Abstract

The 1+/n+ method, based on an ECRIS charge breeder 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 charge breeder 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. Charge breeding efficiencies as well as charge breeding times have been measured for noble gases and alkali elements. The commissioning phase started at GANIL in the second half-year of 2017. It has consisted of a stepwise process to test the upgrade of the SPIRAL1 facility from simple validation (operation of Charge Breeder (CB) as a stand-alone source) up to the production of the first 1+/n+ radioactive ion beam. Thus, this year, a 38m K / 38 K radioactive ion beam has been successfully delivered to a physics experiment over a period of 1 week. The yields on the physics target were in the range of 2-4×10 6 pps at 9 MeV/u. The target ion source system (TISS) was made of a FEBIAD ion source connected to a hot graphite target. This is the first time a radioactive ion beam is accelerated with a cyclotron with the 1+/n+ method. Moreover, a production test with the FEBIAD TISS has confirmed the yields measured previously, which validates the extension of the GANIL/SPIRAL1 catalog for a number of isotopes. In parallel R&D is being performed on new TISSs (e.g. a fast release one, using surface ionization source). Targets are also a subject of ongoing R&D for yield and release time optimization. This contribution will present the new acceleration scheme of the SPIRAL1 facility, which largely extends the palette of RIBs available for nuclear physicists. It will be compared to the ones used at similar ISOL facilities. This facility is more than a simple ISOL facility and an overview of the new opportunities offered by the upgraded installation will be also discussed.

Plasma diagnostic tools for ECR ion sources—What can we learn from these experiments for the next generation sources

“…This is further motivated by the similarity of the simultaneously measured charge breeding times and cumulative confinement times. 23,38 The long ion confinement time is commensurate with the estimate based on the electron density and ion source performance derived from Fig. 2.…”

Improvement of the Efficiency and Beam Quality of the TRIUMF Charge State Booster

“…To improve and optimize the emittance of the extracted beam from the TRIUMF CSB, its extraction system was simulated for the first time with IGUN © code. To gain the required input parameter, the magnetic field distribution of the CSB was modelled and simulated in OPERA and then benchmarked against the measured magnetic field distribution of the GANIL charge state booster [7], a twin source of the TRIUMF CSB. voltage of the CSB and the voltage on the puller electrode which is defined as the extraction voltage was varied and beam emittance with and without magnetic field was calculated.…”

Charge Breeder at GANIL: metal charge-bred elements

“…The SPIRAL1 facility consists of a production cave where the monocharged ion sources are located [1]. Monocharged ions are transported and mass analyzed prior to their injection into the SP1CB.…”

“…The GANIL charge breeder (ECRIS type charge breeder) of the SPIRAL1 facility is now regularly under operation [1][2][3]. After a commissioning phase at LPSC, the SP1CB has been implemented in the SPIRAL 1 beam lines, and has provided in the last 2 years charge-bred ions mostly from alkali elements (stable and radioactive), establishing its ability to deliver intense post-accelerated RIBs of high quality to nuclear physicists.…”

“…

The charge breeder of the SPIRAL1 (SP1CB) facility provided this year to physicists new Radioactive Ion Beams (RIB) for experiments and machine development, showing significantly improved performances compared to those obtained during the initial on-line commissioning of the SPIRAL 1 upgraded facility [1]. These improved performances were obtained thanks to thorough studies conducted off-line with 1+ ion beams produced by FEBIAD and ECR ion sources, successfully demonstrating the ability to couple SP1CB with them.

…”