Asymmetric deformation and N_pN_n scheme

The deformation parameters β and γ of the collective model are basic descriptors of the nuclear equilibrium shape and structure. The evolution of nuclear structure with mass is preliminary a consequence of proton neutron interaction. It is reasonable to suppose that these are the respective number of valance protons and neutrons. There is no distinction between particle and holes and above mid shell N_p or N_n is counted to the next higher magic number. The use of the quantity N_pN_n as a variable to gauge the structure of a given nucleus and to track the evolution of structure is called the N_pN_n scheme. The N_pN_n scheme which has been extensively applied to even-even nuclei is found to be very good bench mark for odd-even, even-odd and doubly odd nuclei as well. In last three decades many researchers had studied the evolution of collective nuclear structure as a function of number of N_pN_n