Identification of excited states in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Bi</mml:mi><mml:mprescripts /><mml:none /><mml:mn>188</mml:mn></mml:mmultiscripts></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Po</mml:mi><mml:mprescripts /><mml:none /><mml:mn>188</mml:mn></mml:mmultiscripts></mml:math>

The neutron-deficient Bi188 and Po188 isotopes have been studied by γ-ray spectroscopy using the recoil-decay tagging technique with Argonne Gas-Filled Analyzer. A new 0.25(5)-μs isomeric state a prompt cascade formed 319-, 366-, 462-keV γ rays established on top of (10−) α-decaying isomer in Bi188. first excited (2+) was identified, its excitation energy 242(2) keV continues nearly constant trend for 2+ states Po190,192,194. is most likely member prolate rotational band built ground state, albeit mixing other coexisting configurations cannot be excluded. results obtained present work provide information to shape coexistence bismuth polonium near neutron midshell at N=104. In this mass region, reduction yield recoil decay observed few nuclides, possible reasons are presented.4 MoreReceived 12 May 2022Accepted 1 August 2022DOI:https://doi.org/10.1103/PhysRevC.106.024317©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasElectromagnetic transitionsIsomer decaysNuclear structure & decaysProperties150 ≤ 189Nuclear Physics