In-Beam γ-Ray Study of ²¹⁷Ra

Abstract

Excited states in ²¹⁷Ra were studied for the first time by the in-beam spectro-scopic techniques. Reactions used were ²⁰⁸Pb(¹²C, 3n)²¹⁷Ra and ¹⁰⁸Pb(¹³C, 4n)²¹⁷Ra at 70 and 80 MeV, respectively. The γ-rays in ²¹⁷Ra were identified based on the γ-ray excitation functions and the αγ-coincidence experiment. The level structure established in this study consists of three streched E2 cascades. Those states are interpreted to arise from the coupling of a valence neutron to the quadrupole- and octupole-phonon. An isomeric state with a half-life of 4.1±0.3 ns was found at 2388 keV with a spin-parity (31/2⁻).