Online coupling of TRIGA-TRAP to the research reactor TRIGA Mainz
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Abstract
Penning traps are versatile tools to gain knowledge about ground state properties of nuclides through high-precision measurements of their atomic masses. They can be used to refine theoretical mass models, thereby contributing to the understanding of nucleosynthesis. The aim of this work was to couple the double-Penning-trap mass-spectrometry setup TRIGA-TRAP to the research reactor TRIGA Mainz to enable mass measurements of short-lived, neutron-rich nuclides produced by neutron induced fission of U-235. These radio nuclides are transported by an aerosol-based gas-jet system and have to be subsequently ionized. For this, a surface ion source was designed and implemented. It enabled a reliable operation at temperatures above 2000 °C and yielded good ionization efficiencies for alkaline metals. The gas-jet was equipped with monitoring devices, which allowed gaining insight into the dependence of its performance as a function of the pressure inside the target chamber. Several beam diagnostics stations were installed along the beamline for extended characterization and optimization studies of individual components.
Ion beams of fission products were generated, mass separated and transformed into ion bunches inside a gas-filled radio frequency quadrupole. The subsequent deceleration from 30 keV to 1.1 keV enabled the injection of radio nuclides into the first Penning trap. Four different short-lived ion species were identified through mass measurements by resonant buffer gas cooling inside this trap. The obtained masses agree with those of the AME2016 within their uncertainties. This dataset is the first obtained for short-lived nuclides at TRIGA-TRAP and confirms the successful transport of fission products from the target to the Penning trap, thereby finalizing the commissioning of TRIGA-TRAP.