QR Code for Mobile users Back bendinginTungsten (W) Isotopes

S Mohammadi, S Mohammadi, Banafsheh Giv
2014 Asian Journal of Engineering and Technology Innovation   unpublished
We have developed a special computing code for calculation of nuclear deformation parameters (β) ofTungsten Isotopes. It has been shown from these calculations that by increasing neutron number, deformation parameter also increase for heavier isotopes which means more deformation from spherical shape. By comparison with Nilsson level diagrams we can infer quadrupledeformation parameter (β 2) of these isotopes. INTRODUCTION We know that nuclei in many cases have large quadruple moments (Q) and
more » ... ey don't behave like a point charge, rather a spherical or elliptical shape with an axis of symmetry is considered for these nuclei. By knowing the quadruple moments, we can measure deformation parameters which can be used to define the shape of nuclei. There are different theoretical and experimental methods for calculation and measurement of nuclear electric quadruple moments [1-7]. In this paper we present a new method for calculation of quadruple moments of Tungsten isotopes. By study of rotational gamma-decay cascades in different bands of these isotopes and drawing the experimental yrast level energies versus moments of inertia for each band, we look for back bending phenomenon[8] for each W isotope. If there is a back bending, then it means that there is a change of moment of inertia,which is happening by excitation of a nucleon to another state with different angular momentum. Thus changing the total spin of nucleus. By comparison with related Nilsson diagram [9], we can find the location of displaced nucleon and thus find the related quadrupledeformation parameter (β 2) at that excitation energy. By finding the deformation parameter we can calculate the quadruple moment of the deformed isotope and study shape changes. Theoretical Calculation and Discussion Nuclei can be obtained in very high angular momentum states, mainly through heavy-ion induced reactions (HI, xn). The states that are populated subsequently decay, through a series of statistical low-spin transitions, into the high-spin lower energies yrast structure. It has been shown that a large amount of angular momenta can be obtained by collective motion (i.e. a coherent contribution of many nucleons to the rotational motion). It is important that the nucleus exhibits a stable, deformed shape. Subsequently, rigid rotation will contribute angular momentum Jand energy E according to the expression