Using β-Decay to Map the E2 Strength in the Cd Isotopes and the Downfall of Vibrational Motion

The β decay of 112Ag has been used to populate spin 0+ and 2+ states in 112Cd to 3 MeV excitation energy. The statistical quality obtained allows the extraction of very weak γ-ray branching ratios that, combined with known level lifetimes, enables the determination of the B(E2) values or upper limits for transitions populating the proposed two-phonon states. While candidates for 3+, 4+, and 6+ three-phonon levels have been identified, there are no candidates for the 0+ and 2+ three phonon levels, and the upper limits of the B(E2) values indicate that phonon E2 strength is not fragmented, but absent below 5ℎω2. (authors)