Berlin 2005 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 35: Instrumentation und Anwendungen

HK 35.6: Group Report

Tuesday, March 8, 2005, 18:15–18:45, TU MA144

First on-line mass measurements at SHIPTRAP — •M. Block — GSI, Planckstrasse 1, D-64291 Darmstadt, Germany

The ion trap facility SHIPTRAP at GSI Darmstadt was set up to enable various experiments on heavy elements produced in fusion evaporation reactions at SHIP. In the first stage SHIPTRAP focuses on precision mass measurements of nuclei not available at ISOL or fragmentation facilities with a Penning trap mass spectrometer. The speciality of SHIPTRAP is the access to the region of the heaviest elements where the majority of masses is only known from extrapolations with a few hundred keV precision. In addition most of the masses in this region are linked to only a few α-decay chains. Hence direct mass measurements from which nuclear binding energies can be deduced are required. The commissioning of SHIPTRAP included extensive off-line tests in order to characterize and optimize all individual components. In on-line experiments the efficiency of the stopping cell was measured with radioactive ions to be 5-8 %. This limits at the moment the overall efficiency of SHIPTRAP. However, mass measurements of radioactive ions with moderate production rates are already feasible. In a beam time in July 2004 radionuclides around ¹⁴⁷Ho were produced in the reaction ⁹²Mo(⁵⁸Ni,xpxn) with a primary beam energy of 4.35 MeV/u. In this run the first mass measurements with the Penning traps were performed. The masses of ¹⁴⁷Ho, ¹⁴⁷Er and ¹⁴⁸Er were measured, the latter ones for the first time.