Nuclear triaxiality in the A ~ 160-170 mass region: the story so far

摘要

Research in nuclear triaxial deformation has revealed many exciting facts and figures over the last one and a half-decades. Although wobbling motion of nuclei was experimentally discovered at the beginning of the last decade, after almost 25 years of its prediction by Bohr and Mottelson, efforts are still being put to understand this rare nuclear phenomenon in greater detail. The concept of transverse wobbling is one such recent attempt which successfully explains the evolution of experimentally observed wobbling frequency with spin. The population of triaxial strongly deformed (TSD) bands in the A~160-170 region is favoured for which neutron number (N = 92 or 94) is a topic of current debate. Experimental efforts are being put following Bengtsson's calculations which indicate that the elevated yrast lines for N = 92 isotones favour TSD population. In A~170 mass region, the ambiguity over the real character of certain strongly deformed bands has recently been removed by extensive experimental and theoretical efforts, and the bands have now been firmly established as either enhanced deformed (ED) or superdeformed (SD).