Lifetime of the two-phonon vibrational state in232Th

Abstract

Abstract.We report on a measurement of the lifetime of the 1414 keV state in 232Th by the Doppler-shift recoildistance method. This 4 + state shows all characteristics of a nearly-harmonic two-phonon 7-vibrational excitation. The result for the B(E2) value obtained from the lifetime, --3.2 _+ 0.7 ps, is in agreement with an earlier estimate of the collectivity from Coulomb-excitation yields and supports the interpretation of the 1414keV state as a two-phonon 7-vibrational excitation.

Lifetime measurements of low-spin negative-parity levels in Gd160

“…The two-phonon γγ vibration in this case is 1.6 times the energy of the single γ-vibrational band. Negative anharmonicities similar to this have been observed in 232 Th [47] in the actinide region and 178 Hf [25] in the rare earths.…”

Two-phononγ-vibrational states in rotating triaxial odd-Anuclei

“…This model gives the K = 4 2γ states in a kinematical manner similar to Davydov-Filippov's asymmetric rotor model [19]. In other mass regions, harmonic 2γ states were observed in 232 Th by Korten et al [20,21] using Coulomb excitation and 106,104 Mo by Guessous et al [22,23] using a spontaneous fission. The latter was discussed from a viewpoint of the X(5) symmetry [24].…”