Shape Changes in Odd-Even Osmium Isotopes

Abstract

This paper has calculated the energy levels of 185-187-189Os isotopes using the projected shell model (PSM). Yrast Spectrum, nucleus rotation frequency and the ratio of reduced electromagnetic transition probabilities, B(E2)/B(M1) plots versus spin for understanding the structure of multi-quasiparticle band up to the spins 47/2+, 33/2+ and 31/2+ for these isotopes, are plotted, respectively. It was found that in the spin ranges 35/2+-39/2+, 31/2+-33/2+, and 27/2+-29/2+, due to 3-quasiparticle band-crossing, simultaneously by increasing rotational inertia of the nucleus, nucleus rotation frequency decreases greatly and as an important result, B(E2)/B(M1) ratio, the electrical properties of the nucleus in these spins increase. Indeed, in these isotopes, observed that by increasing neutron number, the deformation parameter, ε2 decreases as well, and by increasing spin in especial spins, due to nucleon alignment phenomenon, the nucleus rotational behavior decreases inverse the vibration mode.

Keywords

• yrast spectrum
• alignment phenomenon
• electromagnetic transition probability
• projected shell model