Pygmy dipole resonance in 124 Sn populated by inelastic scattering of 17 O

Abstract

The γ decay from the high-lying states of 124 Sn was measured using the inelastic scattering of 17 O at 340 MeV. The emitted γ rays were detected with high resolution with the AGATA demonstrator array and the scattered ions were detected in two segmented Δ E – E silicon telescopes. The angular distribution was measured both for the γ rays and the scattered 17 O ions. An accumulation of E1 strength below the particle threshold was found and compared with previous data obtained with ( γ , γ ′ ) and ( α , α ′ γ ) reactions. The present results of elastic scattering, and excitation of E2 and E1 states were analysed using the DWBA approach. From this comprehensive description the isoscalar component of the 1 − excited states was extracted. The obtained values are based on the comparison of the data with DWBA calculations including a form factor deduced using a microscopic transition density.