The Convection Current for the 0⁺ →1⁺ Excitations in the Even-Even f_7/2 Shell Nuclei

Abstract

The experimental puzzle — a broad bump centered at 10.15 MeV in ⁵¹V is observed in the proton inelastic scattering[1], while there are no strong Ml excitations in the (e,e’) spectra[2] — might suggest the destructive interference of spin and orbital contributions in this energy range, because intermediate energy proton scattering at small angles excites magnetic dipole states only through the spin part of the nucleon-nucleon interaction[3,4], whereas both spin and orbital parts of the electromagnetic interaction may contribute to inelastic electron scattering. In the large scale shell model calculation[5], however, appreciable orbital contribution for T=T_Z states appears below 8.5 MeV, and no appreciable orbital contribution is seen in the excitation energy range where a strong Ml excitation is observed in the (p,p’) reaction. MUTO and HORIE have shown that the strong fragmentation and continuous distribution of the calculated strength in the energy range between 8 and 12 MeV in ^5lV could cause Ml amplitudes to be hardly detected by the (e,e’) measurement, consistent with such an experimental condition that the peak-background ratio of (e,e’) spectra is much smaller than that of (p,p’)[6].