High-spin level structure of the five neutron hole nucleusPb203

Abstract

A pulsed-beam $^{202}\mathrm{Hg}(\ensuremath{\alpha},3n\ensuremath{\gamma})$ experiment has revealed a 0.48-s $^{203}\mathrm{Pb}$ isomer, which deexcites through high-spin positive parity levels to the known ${13/2}^{+}$ state at 825 keV. Comprehensive ($\ensuremath{\gamma}\ensuremath{\gamma}t$) coincidence measurements have established the complete isomeric decay scheme, and key transition multipolarities have been deduced from prompt $\ensuremath{\gamma}$-ray angular distribution data and from intensity balance requirements. The results clearly manifest a close structural relationship between the high-spin levels built on the $^{203}\mathrm{Pb}$ ${13/2}^{+}$ isomer and previously known states of the $^{204}\mathrm{Pb}$ core nucleus. The 0.48-s isomeric state is assigned ${J}^{\ensuremath{\pi}}={\frac{29}{2}}^{\ensuremath{-}}$, with the dominant neutron hole configuration ${(p_{\frac{1}{2}}^{\ensuremath{-}2})}_{0}f_{\frac{5}{2}}^{\ensuremath{-}1}{(i_{\frac{13}{2}}^{\ensuremath{-}2})}_{12}$, and the high-spin positive parity levels are interpreted as members of core hole multiplets of the type $i_{\frac{13}{2}}^{\ensuremath{-}1}\ifmmode\times\else\texttimes\fi{}{2}^{+}$ and $i_{\frac{13}{2}}^{\ensuremath{-}1}\ifmmode\times\else\texttimes\fi{}{4}^{+}$.NUCLEAR REACTIONS $^{202}\mathrm{Hg}(\ensuremath{\alpha},3n\ensuremath{\gamma})$, $E=38.2$ MeV; measured ${E}_{\ensuremath{\gamma}}$, ${I}_{\ensuremath{\gamma}}(\ensuremath{\Theta})$, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coin, $\ensuremath{\gamma}\ensuremath{-}t$ relationships; $^{203}\mathrm{Pb}$ deduced high spin levels, $J$, $\ensuremath{\pi}$, ${T}_{\frac{1}{2}}$.