Spin-vibrational 1+ states in 140Ce

Abstract

The properties of collective I^$\Pi$=1+ states in double even semimagic nucleus 140Ce are investigated in random phase approximation(RPA). The calculation of the B(M1) strength, elastic gamma-scattering cross section $\sigma_(gamma)(\omega)$ and gamma-decay width $\Sigma_(gamma)(\omega_i)$ show that in 140Ce the isovector spin-spin interactions concenrate the main strength of M1 transition at energy 7.89 MeV where the isovector spin-flip magnetic resonance may appear. The predisctions are consistent with the observed M1 strength in 140Ce which is seen to be concentrated within a range of about 0.8 MeV centered at an excitation of 7.95 MeV.