Darmstadt 2008 – scientific programme

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MS: Fachverband Massenspektrometrie

MS 6: Präzisionsmassenspektrometrie und grundlegende Anwendungen

MS 6.5: Talk

Tuesday, March 11, 2008, 15:45–16:00, 3E

Mass Measurements of Rare Isotopes with SHIPTRAP — •Michael Block for the SHIPTRAP collaboration — GSI, Planckstr. 1, 64291 Darmstadt

Accurate mass values of rare isotopes far away from the valley of β-stability are critical for the study of nuclear shell structure and for the benchmarking of nuclear models. Masses of rare isotopes are also of great importance for nuclear astrophysics to support the understanding of nucleosynthesis in the different capture processes. Penning trap mass spectrometers are powerful tools for performing mass measurements with high accuracy. The combination of in-flight separation with gas stopping and advanced ion-beam manipulation techniques has paved the way for mass measurements of rare isotopes produced in fusion-evaporation reactions. With these prerequisites the Penning trap mass spectrometer SHIPTRAP installed behind the SHIP velocity filter has been used for high-precision mass measurements of about sixty neutron-deficient rare isotopes. In two campaigns the masses of nuclei along the pathway of the rapid proton-capture process and of exotic rare-earth isotopes near and beyond the proton drip line were determined. For the first time the mass of the ground state proton emitter ¹⁴⁷Tm was measured. In addition, the location of the proton drip line for holmium was established unambiguously. Recently, a first step toward direct mass measurements of transactinides was made. The isotope ²⁵⁴No was delivered from SHIP at a rate of about 4 ions/s and extracted from the SHIPTRAP gas cell as ²⁵⁴No²⁺ with a rate that is sufficient to perform a direct mass measurement.