Angular correlation of the 1.07-1.24 MeV gamma cascade in the decay of Ga⁶⁸

Abstract

We have measured the angular correlation of the 1.07-1.24 MeV gamma-ray cascade in Zn⁶⁸ following the decay of 68-min Ga⁶⁸. The Legendre polynomial expansion coefficients were determined to be A₂=0.31±0.03 and A₄=0.23±0.07. The measured correlation establishes the spin sequence to be 2-2-0, with a quadrupole-dipole mixing ratio δ of +1.8±0.2 for the 1.24-MeV gamma-ray. The result of the angular correlation work together with the allowed nature (log ft = 5.7) of the electron-capture decay to the 2.3-MeV level fixes the spin and parity of this level to be 2⁺. The results are consistent with the near-harmonic model of Scharff-Goldhaber and Weneser for even nuclei.