Excitations of the Unstable Nuclei

The isoscalar E1 and E2 resonances in the proton-rich nuclei 48,49Ni and the {f7/2⊗ 3−} multiplet in 49Ni have been calculated taking into account the single-particle continuum exactly. The analogous calculations for the mirror nuclei 48Ca and 49Sc are presented. The models used are the continuum RPA for 48Ni, 48Ca and the Odd RPA for 49Ni, 49Sc, the latter has been developed recently and describes both single-particle and collective excitations of an odd nucleus on a common basis. In all four nuclei we obtained a distinct splitting of the isoscalar E1 resonance into 1~ω and 3~ω peaks at about 11 MeV and 30 MeV, respectively. The main part of the isoscalar E1 energyweighted sum rule (EWSR) is exhausted by the 3~ω resonances. The 1~ω resonances exhaust about 35 % of this EWSR in 48,49Ni and about 22 % in 48Ca and 49Sc. All seven {f7/2 ⊗ 3−} multiplet members in 49Ni are calculated to be in the (6–8) MeV energy region and have noticeable escape widths. PACS numbers: 21.60.Jz, 24.30.Cz, 27.40.+z