Dresden 2013 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 57: Poster - Nukleare Astrophysik

HK 57.8: Poster

Wednesday, March 6, 2013, 16:45–19:00, HSZ 4.OG

Mass separation with ISOLTRAP’s MR-ToF — •R. Wolf — Ernst-Moritz-Arndt-Universität, Institut für Physik, 17487 Greifswald

A contaminant-free beam is a crucial condition for mass measurements of short-lived nuclides on an uncertainty level of δ m/m=10⁻⁸, as performed with ISOLTRAP at CERN-ISOLDE. The radioactive beam delivered by an ISOL facility contains a mixture of isobars, where far from stability the ions of interest often amount to only a minute fraction, drowned by contamination. ISOLTRAP has been upgraded with a multi-reflection time-of-flight (MR-ToF) mass analyzer and a Bradbury Nielsen gate, primarily intended as an auxiliary device to provide a faster purification of isobaric mixtures. Mass-resolving power of 10⁵ and a contamination suppression of 10⁴ have been reached in only a few tens of milliseconds, which decreases the purification period by over an order of magnitude compared to mass-selective buffer-gas centering in a dedicated Penning trap. On the one hand, the system can be used as the only mass separator and selector for very short-lived nuclides, where the buffer-gas filled Penning trap acts only for cooling and bunching. On the other hand, for intermediate half-lives and very high contamination to ion of interest ratios, several Penning-trap capture cycles can be performed to filter the few or even the only one ion of interest, for the actual mass measurement. This improves the ion-of-interest throughput by more than a factor of 10. The application of this method, e.g for the mass measurement of ⁸²Zn and its astrophysical impact on the neutron-star crust, will be presented.