First evidence for the hyperdeformed nuclear shape at high angular momentum

Abstract

A ridge structure consisting of stretched E2 transitions and extending from \ensuremath{\Elzxh}\ensuremath{\omega}\ensuremath{\simeq}0.6 to 0.75 MeV has been found in a proton-selected \ensuremath{\gamma}-\ensuremath{\gamma} matrix in the reaction $^{120}\mathrm{Sn}$${(}^{37}$Cl, xn${)}^{152,153}$Dy at 187 MeV. The ridge spacing corresponds to a dynamic moment of inertia, ${\mathit{scrI}}^{(2)}$, of about 130${\mathrm{\ensuremath{\Elzxh}}}^{2}$ ${\mathrm{MeV}}^{\mathrm{\ensuremath{-}}1}$ and suggests the existence of a hyperdeformed prolate shape with a quadrupole deformation ${\mathrm{\ensuremath{\beta}}}_{2}$\ensuremath{\ge}0.9. Furthermore, a cascade of 10 discrete transitions with an average energy spacing of 30\ifmmode\pm\else\textpm\fi{}3 keV has been found. This result is consistent with calculations indicating conditions favorable to hyperdeformed structures.