γdecay to the ground state from the excitations above the neutron threshold in thePb208(p,p′γ)reaction at 85 MeV

Abstract

A new measurement of γ decay from the states above the neutron threshold in Pb208 has been performed at Cyclotron Centre Bronowice in Kraków, Poland. The main goal of the experiment was to observe the γ decay to the ground state from the isoscalar giant quadrupole resonance (ISGQR). To this day, the only published observation of this phenomenon dates back to the late 1980s, where γ decay to the ground state branching ratio was reported. At variance with the existing measurement using inelastic scattering of O17, here proton inelastic scattering is employed. In particular, data were obtained for Pb208(p,p′γ) at 85 MeV beam energy, where γ rays were measured for proton scattering angles 8.9∘, 10.7∘, 12.5∘, and 14.3∘. By applying a similar analysis method as in the previous experiment, the branching ratio of ISGQR gamma decay to the ground state was extracted from the data.1 MoreReceived 22 September 2021Accepted 24 December 2021Corrected 7 February 2022DOI:https://doi.org/10.1103/PhysRevC.105.014310©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCollective levelsElectromagnetic transitionsNuclear structure & decaysNucleon induced nuclear reactionsResonance reactionsProperties190 ≤ A ≤ 219Nuclear Physics