MAGNETIC ROTATION IN NUCLEI OF A =80 AND 130 MASS REGION

Abstract

Quantum systems like molecules and nuclei are known to exhibit collective behaviour which results in the observation of groups of levels forming rotational bands. These bands display particularly simple features like dependence on energy and large intra-band transition probabilities. Generally these features are associated with a deformed density distribution and, therefore, are observed in nuclei which have a deformed shape. Since the lowest and the most common shape in nuclei is quadrupole in nature, the E2 transitions dominate and the levels also follow a general I(I+l) rule. Such structures are quite commonly observed in a large number of nuclei in between the magic numbers. Latest in this class are the super-deformed bands which were observed in nuclei quite close to the magic numbers like Pb isotopes. It is now understood that shell effects can lead to such stabilization and rotational bands. It was quite surprising, therefore, to observe in experiments, rotational like bands in many Pb isotopes which were not super-deformed at all. Observation of such features in many weakly deformed systems was puzzling and challenging as well. A novel explanation for this phenomenon was provided by S. Frauendorf in the form of what is now known as the shears mechanism. Such bands came to be known as magnetic rotation or, shears bands. This thesis presents a mix of experimental and theoretical studies on magnetic rotation bands in the A=80 and 130 mass region.