High-spin structures of five<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="bold-italic">N</mml:mi><mml:mo>=</mml:mo><mml:mn mathvariant="bold">82</mml:mn></mml:mrow></mml:math>isotopes:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mrow/><mml:mrow><mml:mspace width="4pt"/><mml:mn>54</mml:mn></mml:mrow><mml:mn>136</mml:mn></mml:msubsup></mml:math>Xe,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mrow/><mml:mrow><mml:mspace width="4pt"/><mml:mn>55</mml:mn></mml:mrow><mml:mn>137</mml:mn></mml:msubsup></mml:math>Cs,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mrow/><mml:mrow><mml:mspace width="4pt"/><mml:mn>56</mml:mn></mml:mrow><mml:mn>138</mml:mn></mml:msubsup></mml:math>Ba,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mrow/><mml:mrow><mml:mspace width="4pt"/><mml:mn>57</mml:mn></mml:mrow><mml:mn>139</mml:mn></mml:msubsup></mml:math>La, and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mrow/><mml:mrow><mml:mspace width="4pt"/><mml:mn>58</mml:mn></mml:mrow><mml:mn>140</mml:mn></mml:msubsup></mml:math>Ce
Аннотация
Five $N=82$ isotones have been produced in two fusion-fission reactions and their $\ensuremath{\gamma}$ rays studied with the Euroball array. The high-spin states of ${}^{139}$La have been identified, while the high-spin yrast and near-to-yrast structures of the four others have been greatly extended. From angular correlation analysis, spin values have been assigned to some states of ${}^{136}$Xe and ${}^{137}$Cs. Several cascades involving $\ensuremath{\gamma}$ rays of ${}^{139}$La have been found to be delayed; they deexcite an isomeric state with ${T}_{1/2}=315(35)$ ns located at 1800 keV excitation energy. The excited states of these five $N=82$ isotones are expected to be due to various proton excitations involving the three high-$j$ subshells located above the $Z=50$ shell closure. This is confirmed by the results of shell-model calculations performed in this work. In addition, high-spin states corresponding to the excitation of the neutron core have been unambiguously identified in ${}^{136}$Xe, ${}^{137}$Cs, and ${}^{138}$Ba.
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