Description of the low-lying levels inCd112,114

Starting from a simplified model, treating proton two-particle two-hole excitations in interaction with low-lying quadrupole vibrational configurations, we calculate the low-lying levels in even-even ${}_{}{}^{112,114}{}_{}{}^{}\mathrm{Cd}$. We also present configuration mixing calculations within the framework of the interacting boson model. Both approaches give a good description of the quintuplet of levels occurring below $E_x\cong 1.5$ MeV in ${}_{}{}^{112,114}{}_{}{}^{}\mathrm{Cd}$ (energy spectra and a detailed account of $E2$ and $E0$ decay properties). Finally, we point out some similarities between both approaches and try to interpret the interacting boson model mixing parameters in terms of shell-model quantities (two-body matrix elements and single-particle energies).