Study of the γ decay of high-lying states in ²⁰⁸Pb via inelastic scattering of ¹⁷O ions

Dipartimento di Fisica dell′Università di Milano e INFN, I-20133 Milano, Italy

Abstract

High-lying states in ²⁰⁸Pb nucleus were populated via inelastic scattering of a ¹⁷O beam at bombarding energy of 20 MeV/u. Their subsequent gamma decay was measured with the detector system AGATA Demonstrator based on HPGe detectors, coupled to an array of large volume LaBr₃:Ce scintillators. Preliminary results in comparison with (γ,γ′) data, for states in the 5–8 MeV energy interval, seem to indicate that in that region the states belong to two different groups one with a isoscalar character and the other with a isovector nature. This is similar to what was observed in other stable nuclei with (α,α′γ) experiments. The multipolarity of the observed gamma transitions is determined with remarkable sensitivity thanks to angular distribution measurements. Data aiming at studying the neutron decay of the Giant Quadrupole Resonance in the ²⁰⁸Pb by the high resolution measurement of the following gamma decay are also presented in their preliminary form.