Mass measurements and production of ions at IGISOL for the astrophysical r- and rp-processes

Abstract

The masses of 27 nuclear ground states and three isomeric states have been measuredwith the JYFLTRAP double Penning trap mass spectrometer at the IonGuide Isotope Separator On-Line (IGISOL) facility. The studied nuclides are locatedin two separate regions of the nuclear chart, the neutron-rich rare-earthregion around A ≈ 160 and the neutron-deficient A ≈ 80 region near the N = Zline. The mass measurements were performed using the the Time-of-Flight Ion-Cyclotron Resonance and Phase-Imaging Ion-Cyclotron Resonance techniques.The impact of the measured masses on the astrophysical rapid neutron captureprocess (r-process) was studied for several trajectories representing a neutronstarmerger scenario. The masses of two nuclides near the N = Z line werepredicted using mirror displacement energies and the masses of their mirror partnersmeasured in this work. Additionally, the effects of the measured masses onnuclear structure and the mass surface in both regions of the nuclear chart werestudied. An upgraded version of the Heavy-ion Ion Guide Isotope Separator On-Line (HIGISOL) system for the production of radioactive ions using heavy-ionbeams has been commissioned and successfully used in its first on-line experiment.The new off-line ion source facility has been brought into routine use at theIGISOL facility and used in various experiments. Systematic studies on the effectof ion count rate on mass measurements at JYFLTRAP have been performedusing stable ion beams from the new ion source station.Keywords: Penning trap, r-process, nuclear structure, IGISOL, off-line ion beams,systematic uncertainty