Lifetime measurements of excited states in Pt 172 and the variation of quadrupole transition strength with angular momentum

Lifetimes of the first excited 2þ and 4þ states in the extremely neutron-deficient nuclide 172Pt have been measured for the first time using the recoil-distance Doppler shift and recoil-decay tagging techniques. An unusually low value of the ratio BðE2∶4þ 1 → 2þ 1 Þ=BðE2∶2þ 1 → 0þ gsÞ ¼ 0.55ð19Þ was found, similar to a handful of other such anomalous cases observed in the entire Segr´e chart. The observation adds to a cluster of a few extremely neutron-deficient nuclides of the heavy transition metals with neutron numbers N ≈ 90–94 featuring the effect. No theoretical model calculations reported to date have been able to explain the anomalously low BðE2∶4þ 1 → 2þ 1 Þ=BðE2∶2þ 1 → 0þ gsÞ rati…