Comparison of the six states recently observed in ' Ho with the states in ' Ho suggests configurational assignments for all six states. The validity of these assignments is strengthened by the allowed unhindered beta decay of ' Dy to the two 1+ states in ' Ho and by microscopic theoretical calculations of the quasiparticle structure of the corresponding states in ' Ho and ' Ho.
I. INTRODUCTIONRecently, six low-lying states in ' Ho have been studied [1] following their population in the beta decay of Dy. Three firm and three tentative spin assignments were made to these six states. The first excited state with tentative spin 6+ is a 132-s isomer. These states and their assignments are shown to the left in Fig. 1.
II. EXPERIMENTAL COMPARISON OF 166Ho AND 168HoThe states in ' Ho are also compared with the ' Ho states with known spin, parity, and Nilsson assignments [2] in Fig. 1. The energies and spins in '6 Ho and '66Ho are shown to the left and right, respectively, of the appropriate levels. A11 of the levels in ' Ho are lowered by 190.9 keV except the 1+ at 567.6 keV. This is done to put the -', +[523] --, ' [521] states in ' Ho and ' Ho at the same energy for the sake of comparison. The lowest five states in Fig. 1, all of which are neutron particle states in ' Ho, are expected to move coherently to facilitate this comparison. Only the 1+ state at 567.6 keV in Ho, which is a neutron hole state, is expected to move in the opposite direction. To take this into account it is raised by 190.0 keV rather than lowered on the relative energy scale. It should be noted that listed energies of the levels are those experimentally observed while the relative energies are those shown by the positions of the levels.When these adjustments are made, as shown in Fig. 1, the comparison of the level energies in ' Ho and ' Ho is quite remarkable. The agreement in the level schemes gives us confidence that the assignments which are known for ' Ho apply also to ' Ho. In addition, they tend to verify the assignments made in Ref.[1].The allowed unhindered ( A U) beta decays from ' Dy and ' Dy into the 1+ isobaric states of ' Ho and ' Ho, respectively, because of their uniqueness, are particularly powerful spectroscopic tools in assigning configurations.