A superdeformed rotational band has been identified in ${}^{36}\mathrm{Ar}$, linked to known low-spin states, and observed to its high-spin termination at $I^{\pi }{=16\mathrm{}}^{+}$. Cranked Nilsson-Strutinsky and spherical shell model calculations assign the band to a configuration in which four $\mathrm{pf}$-shell orbitals are occupied, leading to a low-spin deformation ${\beta }_2\approx 0.45$. Two major shells are active for both protons and neutrons, yet the valence space remains small enough to be confronted with the shell model. This band thus provides an ideal case to study the microscopic structure of collective rotational motion.

• Received 8 May 2000

DOI:https://doi.org/10.1103/PhysRevLett.85.2693