Octupole correlations in the ¹¹⁴Xe nucleus determined through linear polarization analysis with EUROBALL

Abstract

Octupole correlations have been suggested to be present at low and medium spin in the light Te, I and Xe nuclei. In this mass region the Fermi surface for both protons and neutrons lies between the d _5/2 and the h _11/2 orbitals. Experimentally octupole correlations have been suggested in the light Xe and Te nuclei based on electric dipole (E1) transitions linking the rotational sequences whose character has been inferred only from branching ratios and angular behaviour. Since the experimental confirmation of the electric character of these dipole transitions is paramount in order to firmly establish the octupole nature of such excitations, we have investigated at EUROBALL the linear polarization of the γ rays deexciting such nuclei. In the present work we report the linear polarization and lifetime results obtained for the ¹¹⁴Xe nucleus. Moreover the observation of two E3 transitions deexciting the 5⁻ and 3⁻ states of the octupole sequence has allowed a quantitative determination of the octupole collectivity. High-spin states in the neutron deficient nucleus ¹¹⁴Xe were populated using the ⁵⁸Ni + ⁵⁸Ni reaction at 210 MeV.