A new device for combined Coulomb excitation and isomeric conversion electron spectroscopy with fast fragmentation beams

Abstract

A new setup has been designed to perform Coulomb excitation experiments with fragmentation beams at intermediate energy and to measure at the same time conversion electrons from isomeric states populated in the fragmentation reaction. The newly designed setup is described and experimental results from a first experiment are shown. Radioactive even–even nuclei in the mass region A ≃ 70 close to the N = Z line were Coulomb excited after fragmentation of an intense primary 78Kr beam and selection in flight with the LISE3 spectrometer at GANIL. The γ rays emitted after Coulomb excitation were detected in an array of four large segmented HPGe clover detectors in a very close geometry. The scattered ions were identified in a stack of highly segmented annular silicon detectors combined with a time-of-flight measurement using beam tracking detectors. Conversion electrons from isomeric 0 2 + states decaying via electric monopole transitions were detected in an array of segmented cooled silicon detectors surrounding a telescope of plastic scintillators. Reduced transitions probabilities B ( E 2 ; 0 1 + → 2 1 + ) were deduced for several stable and radioactive nuclei.