<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math>Decay of Neutron-Deficient Odd Bi Nuclei: Shell-Model Intruder States in Tl and Bi Isotopes

Abstract

The $\ensuremath{\alpha}$ decay of mass-separated Bi isotopes is studied to characterize the shell-model intruder states in the odd-mass Tl and Bi isotopes. Allowed $\ensuremath{\alpha}$ decay is observed between the $^{189\ensuremath{-}195}\mathrm{Bi}$ $\ensuremath{\pi}{h}_{\frac{9}{2}}$ ground states and the $^{185\ensuremath{-}191}\mathrm{Tl}$ $\ensuremath{\pi}{h}_{\frac{9}{2}}$ intruder states and between the $^{191\ensuremath{-}197}\mathrm{Bi}$ $\ensuremath{\pi}{s}_{\frac{1}{2}}$ intruder states and the $^{187\ensuremath{-}193}\mathrm{Tl}$ $\ensuremath{\pi}{s}_{\frac{1}{2}}$ ground states. The observation of forbidden $\ensuremath{\alpha}$ branches provides excitation energies for the intruder states in $^{189,191}\mathrm{Tl}$ and $^{189,191,193,195}\mathrm{Bi}$ and confirms the intruder-state excitation energies in $^{185,187}\mathrm{Tl}$.