Nuclear Spectroscopy of N=50 Isotones With 29 ≤ Z ≤ 36

摘要

At the two extremes of proton and neutron rich sides, two doubly magic nuclei ~(48)Ni and ~(78)Ni have remarkable interest. The former is a prime candidate for the two proton radioactivity, whereas the second is an important waiting point in the path of the rapid-neutron-capture process. The N=50 is situated deep into exotic region and Z=28 is a well established proton gap. So the doubly closed ~(78)Ni with an unusual proton to neutron ratio, lies between two regions:of the light nuclei, where experimental evidence for changing magic numbers going far from stability is well established, and of heavy ones, where no quenching of the known spin-orbit shell closures has been observed. From N=40, when neutron filling is done up to N=50, the Z=28 gap formed between f_(7/2) and g_(9/2) orbits changes from 6 MeV in ~(68)Ni to around 3.5 MeV in the ~(78)Ni. In such cases, increased proton excitation across Z=28 gap or core polarization would be expected. ~(78)Ni is therefore an interesting region to study the validity of nuclear shell model in modeling the available experimental nuclear data. Studying the nucleus around ~(78)Ni is expected to shed light on whether the shell closure at N=50 will be hold or not as protons are filled above the Z=28. So the study of region of medium mass nucleus around ~(78)Ni i.e. Z=28 and N=50 will give useful information about it.In the present work we have performed large scale shell model calculations for N=50 isotones with 29 ≤ Z ≤ 36 namely odd mass nuclei ~(79)Cu, ~(81)Ga, ~(83)As, ~(85)Br and even mass nuclei ~(80)Zn, ~(82)Ge, ~(84)Se, ~(86)Kr. The aim of this work is to study the evolution of shell structure for nuclei close to drip line as the proton number changes in this mass region.