Lifetimes have been measured in a superdeformed rotational band recently id
entified in the N=Z nucleus Ar-36. A large low-spin quadrupole deformation
(beta (2) = 0.46 +/- 0.03) is confirmed and a decrease in the collectivity
is observed as the high-spin band termination at I-pi = 16(+) is approached
. Detailed comparisons of the experimental B(E2) values with the results of
cranked Nilsson-Strutinsky and large-scale (s(1/2)d(3/2))-pf spherical she
ll model calculations indicate the need for a more refined treatment of tra
nsition matrix elements close to termination in the former, and the inclusi
on of the complete sd-pf model space in the latter description of this high
ly-collective rotational band.