Lifetime measurement in excited and yrast superdeformed bands inHg194

Nuclear level lifetimes have been measured in two superdeformed bands in ${}_{}{}^{194}{}_{}{}^{}\mathrm{Hg}$ using the Doppler-shift attenuation method. Average transition quadrupole moments derived from the lifetimes of an excited and yrast superdeformed bands are ${\mathit{Q}}_{\mathit{t}}$=17.6(30) and 17.2(20)eb, respectively. The Doppler shifts of the excited band relative to the yrast band indicate a slight difference in quadrupole moments [+4(5)%], assuming similar side feeding..ul2 These results imply that the second well is stable and rigid with respect to the particle excitation responsible for this excited band.