First evidence for triaxial superdeformation in Hf-168

Three superdeformed (SD) bands have been found in Hf-168. Lifetime measurem ents revealed a large quadrupole moment, Q(t) similar to 11.4 e b, for the strongest band (TSD1). Theoretical calculations using the Ultimate Cranker code predict high-spin SD minima (epsilon (2) similar to 0.43) with stable triaxial deformations of gamma similar to +20 degrees and gamma similar to -15 degrees. The measured Q(t) value suggests that band TSD1 corresponds, m ost likely, to a deformation with a positive gamma value. This constitutes the first evidence for triaxial superdeformation in an even proton system. (C) 2001 Published by Elsevier Science B.V.