Core polarization in the light of new experimental g factors of fp shell, N=28, isotones - art. no. 031301

Precise experimental g factors of the first 2(+) states of Ti-50, Cr-52, an d Fe-54 have been measured. They differ markedly from the g factors of the (7/2)(-) ground states of the odd-mass neighbors. The experimental results show that the g factors, g(2(1)(+)) and g ((7/2)(-)), lie approximately on straight lines as a function of Z albeit with different slopes. Shell model calculations were performed in which up to t nucleons were excited from th e f(7/2) shell. The data are reproduced by calculations using the FPD6 inte raction with t=1. However, the slope flattens out in the calculations with higher t. The sign of a key matrix element which allows for f(5/2) admixtur e is positive for the FPD6, zero for the KB3, and negative for the FPY inte ractions, respectively, indicating that a better understanding of the effec tive interaction in this region is needed.