Mass measurements of exotic nucildes with TITAN at TRIUMF (Vancouver, Kanada)

• Applicant: Professor Dr. Christoph Scheidenberger
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2019 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 422761894

The aim of modern nuclear physics is the exact understanding of the strong force with the ultimate goal of deriving the structure of atomic nuclei and the variety of observed phenomena from a few fundamental interactions and to determine the Hamiltonian, which can accurately and completely describe the many-particle system of the atomic nucleus. Today, precision mass measurements of so-called "exotic" (i.e. radioactive) nuclei play a prominent role. In recent years, a new time-of-flight mass spectrometer (MR-TOF-MS) has been developed by us and installed at the TITAN experiment at TRIUMF, one of the world's leading laboratories in this field. The MR-TOF-MS features a unique combination of performance characteristics (speed, sensitivity, accuracy). The instrument can be used for three different purposes: beam diagnostics / development, isobar separation and precision mass measurements; in all three modes the instrument supports and improves the already existing instrumentation of TRIUMF and the TITAN experiment. It allows the laboratory to offer more beams than before, and the existing ones are improved in quality and purity. After commissioning and successful first tests and measurements with stable and exotic beams it is ready for experiments with the TRIUMF accelerator. The proposed mass measurements aim at nuclear structure investigations far from the stability and selected, important questions of nuclear astrophysics. Experiments are planned on neutron-rich gallium isotopes, which are important in the "weak" r process (approved LOI1699). The predictions of existing mass models differ so strongly that the rprocess yields obtained with network calculations differ by up to two orders of magnitude; this discrepancy can only be resolved by direct mass measurements. The nuclear shell at N = 82 will be investigated by measurements of proton-rich lutetium, ytterbium and thulium isotopes (approved beam time proposal S1746). This will also constitute the test of the shell structure farthest from the valley of stability sofar. There are further approved beam time proposals, which will be supported in the context of this proposal. Furthermore, the MRTOF- MS will not only be used for mass measurements, but also its full apllication as isobar separator together with the electron beam ion trap and Penning traps will be enabled and used. Finally, improvements of the MR-TOF-MS will be implemented, which will further increase the performance of the MR-TOF-MS.

• DFG Programme: Research Grants
• International Connection: Canada
• Co-Investigators: Dr. Timo Dickel, Ph.D.; Dr. Wolfgang Rüdiger Plaß
• Cooperation Partners: Professor Dr. Jens Dilling; Professorin Dr. Ania Kaiatkowski; Professor Dr. Reiner Krücken