In-beam study of the level crossing resonance on the 4 μs 2 9+ isomer of 69 Ge in a Zn single crystal

The time-integral angular distribution was measured as a function of an external magnetic field for γ-rays from the 398 keV 2 9+ state of69Ge populated by bombarding a Zn single crystal with a natural α-beam from a cyclotron. Clear resonances of dispersion as well as Lorentz type having a narrow width consistent with the natural width (τ=4 μs) were observed at Bres=9.15 kG corresponding to the first level-crossing resonance of the 2 9+ state due to the combined collinear magnetic and quadrupole interactions. The effects of noncollinearity were also demonstrated and compared with theory. As an application of this resonance method, the temperature dependence of the quadrupole interaction frequency was measured.