Low-energy excitations and $$\gamma $$-decay branchings in $$^{124}$$Sn via (p,p’$$\gamma $$) at $$E_p={15}\,\,\hbox {MeV}$$

Abstract

The dipole response of the proton-magic nucleus $${}^{124}\hbox {Sn}$$ 124 Sn was previously investigated with electromagnetic and hadronic probes. Different responses were observed revealing the so-called isospin splitting of the Pygmy Dipole Resonance (PDR). Here we present the results of a new study of $${}^{124}\hbox {Sn}$$ 124 Sn using inelastic proton scattering at low energies to test an additional probe possibly exciting states of the PDR. The response to the new probe as well as the $$\gamma $$ γ -decay behavior of excited states were studied. The $${}^{124}\hbox {Sn}$$ 124 Sn (p,p’$$\gamma $$ γ ) experiment was performed at $$E_p = {15}\,\,\hbox {MeV}$$ E p = 15 MeV using the combined spectroscopy setup SONIC@HORUS at the Tandem accelerator of the University of Cologne. Proton-$$\gamma $$ γ coincidences were recorded, enabling a state-to-state analysis due to the excellent energy resolution for both particles and $$\gamma $$ γ rays. $$ J=1 $$ J = 1 states in the PDR region were populated in the present inelastic proton scattering experiment. Many $$\gamma $$ γ -decay branching ratios could be determined.