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

Abstract

The γ decay from the high-lying states of ¹²⁴Sn was measured using the inelastic scattering of ¹⁷O 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 $\mathrm{\Delta }E\text{–}E$ silicon telescopes. The angular distribution was measured both for the γ rays and the scattered ¹⁷O ions. An accumulation of E1 strength below the particle threshold was found and compared with previous data obtained with ($\gamma ,{\gamma }^{\prime }$) and ($\alpha ,{\alpha }^{\prime }\gamma$) 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.