Damping of high-energy particle-hole-type nuclear excitations: A semimicroscopic model

Abstract

Abstract.A semi-microscopic model (particle-hole dispersive optical model) is formulated to describe the main relaxation modes of high-energy particle-hole-type excitations in medium-heavy mass nuclei. Within this model Landau damping and the single-particle continuum are considered microscopically, while the spreading effect is treated phenomenologically with taking a statistical assumption into account. Description of directnucleon-decay properties of the above-mentioned excitations (including giant resonances) is a unique feature of the proposed model, which in applying to closed-shell nuclei is arranged for practical implementations.

Damping of simple modes of high-energy nuclear excitations: dispersive optical models and their implementations

“…Being the phenomenological quantity, the imaginary part of the mentioned strength, W(ω), determines the real part, P(ω), via the proper dispersive relationship [3,10]. The comments to derivation of the basic expression (2) are the following [3]. To realize the abovementioned statistical assumption, we start from the integral equation for the non-local (non-averaged) "free" p-h Green function A 0 (x, x 1 ; x , x 1 ; ω):…”

“…(It is supposed, that the spreading effect appears at a finite excitation energy ω min = ∆). The dispersive relationship is properly adopted [3,10].…”

“…The simplified form of the expression (8), in which the optical-model strength function φ (+) ε is used instead of φ (−) * ε has been proposed in Ref. [3]. Such a substitution is valid only within the cRPA.…”

“…In this talk we present, in the main, the recently developed [3] particle-hole dispersive optical model (PHDOM), its unique features, new developments and some implementations. In applying to the description of deep-hole states, an unitary version of single-quasiparticle dispersive optical model (SQDOM) [4] is also briefly presented.…”

Properties of isoscalar monopole particle-hole-type excitations in208Pb

“…In the present work we use the particle-hole dispersive optical model (PHDOM) developed recently [3] to describe in a semi-microscopic way, and in average over the energy, some properties of high-energy isoscalar monopole (p-h)-type excitations in 208 Pb. The other aim of this study is to examine from a microscopic point of view the applicability of the quasiclassical collective model transition densities of the ISGMR and its overtone (ISGMR2) to the description of these resonances.…”