Transitional ${\hat{I}}^3$ strength in Cd isotopes

Abstract

The level densities and ${\hat{I}}^3$-ray strength functions of ${}^{105,106,111,112}$Cd have been extracted from particle-${\hat{I}}^3$ coincidence data using the Oslo method. The level densities are in very good agreement with known levels at low excitation energy. The ${\hat{I}}^3$-ray strength functions display no strong enhancement for low ${\hat{I}}^3$ energies. However, more low-energy strength is apparent for ${}^{105,106}$Cd than for ${}^{111,112}$Cd. For ${\hat{I}}^3$ energies above $\approx$ 4 MeV, there is evidence for some extra strength, similar to what has been previously observed for the Sn isotopes. The origin of this extra strength is unclear; it might be due to $E1$ and $M1$ transitions originating from neutron skin oscillations or the spin-flip resonance, respectively.

10 pages, 11 figures