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MS: Massenspektrometrie

MS 6: Präzisions-MS kurzlebiger Nuklide 2

MS 6.1: Hauptvortrag

Donnerstag, 16. März 2006, 10:40–11:10, H1

Mass measurements around ¹⁴⁷Tm at SHIPTRAP — •Michael Block — GSI, Planckstrasse 1, 64291 Darmstadt

The determination of masses of rare radionuclides gives access to nuclear binding energies and is a useful tool supporting the understanding of the fundamental interactions in nuclei. At accelerator facilities world-wide measurements close to the limits of stability are pursued. Penning trap mass spectrometers have proven to be powerful tools for that purpose offering an unmatched precision combined with a high resolving power to identify isomeric states even with low excitation energies.

The Penning trap mass spectrometer SHIPTRAP at GSI was set up for precision mass measurements of heavy radionuclides produced in fusion reactions and separated by the velocity filter SHIP. This production scheme offers the unique possibility to access the region of elements heavier than uranium where only few masses have been experimentally determined up to now. The main challenge in this region is given by the low production rate of the interesting nuclides.

In first experiments the region of proton-rich rare earth nuclides near the proton drip-line was investigated. The nuclides were produced in the reaction ⁹²Mo(⁵⁸Ni,xpyn) at SHIP with primary beam energies between 4.36 to 4.6 MeV/u. In two runs the mass of 17 nuclides was measured including the ground state proton emitter ¹⁴⁷Tm with a half-live of 580 ms and its daughter ¹⁴⁶Er. Since the production rate of ¹⁴⁷Tm is only about a factor of ten higher than for nobelium, a mass measurement of nobelium is in reach.