Pigmy and soft dipole states in nuclei far from the stability line
نویسندگان
چکیده
Pigmy and soft-dipole states in light drip-line nuclei are investigated by large-scale shell model calculations. Large E1 strength is found in the low-excitation-energy region below 5MeV in halo or skin nuclei such as 11Li, 12Be, and 13O. Both the effects of the extended halo or skin wave functions and the coherence in the transition amplitudes are important for enhancing the E1 strength. The particle (hole)-vibration coupling model is presented to explain the splitting of the low-energy E1 strength in 11Li and 13O. Melting of the shell magicity at N = 8 and Z = 8 is pointed out. Pigmy resonances in oxygen isotopes are also studied.
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