Mass measurements of neutron-rich isotopes near N=20 by in-trap decay with the ISOLTRAP spectrometer

Abstract

The masses of Si34, Mg33,34, and Al34 have been measured with the ISOLTRAP Penning-trap spectrometer at ISOLDE/CERN. The results are in agreement with previous mass measurements and uncertainties have been decreased. The mass of Al34 was determined in two configurations, one following direct production by the ISOLDE facility, favoring the 4- state, expected to be the ground state, second by in-trap decay of Mg34, followed by recoil-ion trapping, favoring the production of the isomeric 1+ state. A position-sensitive detector was used to clean the ToF-ICR resonance. In addition, the mass of the refractory doubly magic Si34 nucleus was directly measured, using the in-trap decay of Mg34, following two sequential recoil-ion captures. The approach, challenges and conclusions are discussed.