States of167Ho from the decay of neutron rich nuclide167Dy

Theβ ^?-decay of ₆₆ ¹⁶⁷ Dy produced through the fast neutron reaction¹⁷⁰Er(n, α)¹⁶⁷Dy has been investigated by using several kinds of detectors and a high-capacity two-parameter recording system. The half-life andβ ^?-decay energy of¹⁶⁷Dy were determined to beT _1/2 = 6.20 ± 0.08min andQ _β-=2.35±0.06, respectively. The observed level scheme of ₆₇ ¹⁶⁷ Ho (completely unknown previously) contains 12 states, among them a 6.0±0.1 μsM2 isomer at 259.3 keV. On the basis of theoretical and systematic considerations combined with multipole determinations, the following Nilsson model assignments are proposed for the lowest states of¹⁶⁷Ho: 0 keV (7?/2 [523]), 259.3 keV (3+/2[411]), 319.8 keV (5/2 3+/2[411]), 392.5 keV (1+/2[411]), 410.0 keV (3/2 1+/2[411]), 569.7 keV (3?/2{7?/2[523], 2⁺}). Theβ-decay proceeds mainly to the proposed gamma-vibrational state at 569.7 keV with an anomalously low logft value 5.4, indicating similarity between the microscopic structures of this state and the famous ¦K ₀?2¦ gamma vibration of¹⁶⁵Ho.