عنوان البحث(Papers / Research Title)
The effect of core polarization on longitudinal form factors in B10
الناشر \ المحرر \ الكاتب (Author / Editor / Publisher)
فؤاد عطية مجيد
Citation Information
فؤاد,عطية,مجيد ,The effect of core polarization on longitudinal form factors in B10 , Time 09/05/2012 04:43:02 : كلية التربية للعلوم الصرفة
وصف الابستركت (Abstract)
Core polarization effect are included though microscopic theory to study the C2 form factors of 1pshell B10 nucleus.
الوصف الكامل (Full Abstract)
Abstract:
Electron scattering Coulomb form factors for the singleparticle quadrupole transitions in the pshell 10B nucleus have been studied. Core polarization effects are included through a microscopic theory that includes excitations from the core orbits up to higher orbits with (2 hbar omega) excitations. The modified surface delta interaction is employed as a residual interaction. The effect of core polarization is found essential in both the transition strengths and momentum transfer dependence of form factors, and gives remarkably good agreement with the measured data with no adjustable parameters.
1. Introduction
Comparisons between calculated and measured longitudinal electron scattering form factors have long been used as stringent tests of models of nuclear structure [1, 2]. Shell model within a restricted model space succeeded in describing static properties of nuclei when effective charges are used. The Coulomb form factors have been discussed for the stable sdshell nuclei using sdshell wave functions with phenomenological effective charges [3]. For pshell nuclei, the Cohen–Kurath (CK) [4] model explains the lowenergy properties of pshell nuclei well. However, at highermomentum transfer, it fails to describe the form factors. Radhi et al [5–9] have successfully proved that the inclusion of core polarization (CP) effects in the pshell and sdshell is essential to improve the calculations of the form factors. Restricted 1pshell models were found to provide good predictions for the 10B natural parity level spectrum and transverse form factors [10]. However, they were less successful for C2 form factors and give just 45% of the total observed C2 transition strength. Expanding the shellmodel space to include (2 hbar omega) configurations in describing the form factors of 10B, Cichocki et al [10] found that only a 10% improvement was realized. The purpose of this work is to study the C2 form factors for 10B by including higherenergy configurations as a firstorder CP through a microscopic theory, which combines shell model wave functions and highly excited states.Singleparticle wave functions are used as a zeroth contribution and the effect of CP is included as a firstorder perturbation theory with the modified surface delta interaction (MSDI) [11] as a residual interaction and a (2 hbar omega) for the energy denominator. The singleparticle wave functions are those of the harmonicoscillator (HO) potential with size parameter b chosen to reproduce the measured rootmeansquare (rms) charge radii of these nuclei.
2. Theory
The CP effect on the form factors is based on a microscopic theory, which combines shell model wave functions and configurations with higher energy as firstorder perturbations; these are called CP effects. The reduced matrix elements of the electron scattering operator T3 are expressed as the sum of the product of the elements of the onebody density matrix (OBDM). where and label singleparticle states (isospin is included) for the model space. For pshell nuclei, the orbits 1p3/2 and 1p1/2 define the model space. The states 0i i and 0f are described by the model space wave functions.Greek symbols are used to denote quantum numbers in the coordinate space and isospace.
Dear interested reader to read the full paper, kindly see the attached PDF file. This paper is accepted for publication at 16 April, 2012 and Published online at 9 May, 2012 by Physica Scripta, by the IOP Science on behalf of the Royal Swedish Academy, Phys. Scr. 85 (2012) 065201. http://dx.doi.org/10.1088/00318949/85/06/065201
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