High-precision Penning-trap mass measurements of long-lived transuranium nuclides at TRIGA-TRAP

TRIGA-TRAP, currently located at the TRIGA research reactor in Mainz, has access to thermal neutron-induced fission products of 235U, 239Pu or 249Cf. The on-line commissioning at the research reactor is ongoing. In parallel, we have developed an off-line laser-ablation ion source featuring a buffer-gas-filled miniature radio-frequency quadrupole trap structure. Employing this ion production technique, we have carried out a number of high-precision off-line mass measurements. Recently, the absolute masses of four long-lived transuranium nuclides, 241Am, 243Am, 244Pu, and 249Cf have been measured with TRIGA-TRAP. Our measurements confirm the AME 2012 mass values of 241Am, 243Am and 244Pu within one standard deviation, which were indirectly determined by decay spectroscopy studies. In the case of the 249Cf mass, a discrepancy of more than three standard deviations has been observed, affecting absolute masses even in the superheavy element region. Implementing our directly measured mass values into the AME reduced the mass uncertainties for 84 nuclides. Our aim is to perform further measurements in this region to study the deformed N=152 neutron shell closure, recently investigated at SHIPTRAP. Our new ion source is capable to operate with relatively small samples, down to 1015 atoms deposited on a target. The achieved performance enables us to employ our ion source in the 163Ho - 163Dy Q-value determination relevant for neutrino physics. In the future extremely rare isotopes of all elements up to uranium will be available at the FAIR facility behind the in-flight separator Super-FRS, where TRIGA-TRAP will be installed as MATS within NUSTAR. The present status of the TRIGA-TRAP experiment will be summarized focusing on recent results and technical developments.