Production of actinide atomic and molecular ion beams at CERN-ISOLDE
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Abstract
The Isotope Separation On-Line method is used to produce radioactive ion beams at the CERN-ISOLDE facility. This work investigates applying the method to deliver ion beams of actinide elements.
Actinide nuclides were produced in nuclear reactions with 1.4-GeV protons incident on a bulk target. They were extracted, delivered to experimental stations and identified through measurements of their unique properties. The production of atomic ion beams was investigated for the elements with atomic numbers 89-94. Actinium was ionized using resonance laser ionization. The elements neptunium and plutonium were identified for the first time at ISOLDE.
Molecular formation was used to extract actinides as molecular fluoride ion beams, which were identified by decay spectroscopy measurements as well as by time-of-flight mass measurements. Successful production of AcF+ enabled the first laser spectroscopy studies of the AcF molecule. Molecules were also formed from the mass-separated ion beams in a gas-filled radio-frequency-quadrupole ion trap by reactions with residual gas impurities, providing a method to produce molecules at ambient temperature.
ISOLDE's offline 2 mass separator facility has been upgraded with two new gas systems and time-resolved single-ion-counting data acquisition for future developments.