Lorentzian-like models of E1 radiative strength functions. V. A. Plujko, O. M. Gorbachenko, E. V. Kulich Taras Shevchenko National Kyiv University, Ukraine. Content. Introduction: average description of the gamma-transitions by the use of radiative strength function (RSF).
Lorentzian-like models of E1 radiative strength functions
V. A. Plujko, O. M. Gorbachenko,E. V. Kulich
Taras Shevchenko National Kyiv University, Ukraine
Gamma-emission is the most universal channel of the nuclear decay, because it is, as a rule, realized during emission of any particle or cluster. The strengths of electromagnetic transitions between nuclear states are much used for investigations of nuclear models, mechanisms of -decay, width of the collective excitations and nuclear deformations.
Average strengths of - transitions are described by radiative strength functions.
It is very important for decreasing in computing time to use simple closed-form expressions for -ray strength functions, since these functions in the most cases are auxiliary quantities required for calculations of other nuclear reaction characteristics.
The goal of this contribution is to overview and test practical methods for the calculation of E1 radiative strength functions both for -decay and photoabsorption.
The photoexcitation strength function
The gamma-decay strength function
Mainclosed-form models of E1 RSF
Standard Lorentzian (SLO)[D.Brink. PhD Thesis(1955); P. Axel. PR 126(1962)]
Enhanced Generalized Lorentzian (EGLO)
[J.Kopecky , M.Uhl, PRC47(1993)]
[S.Kadmensky, V.Markushev, W.Furman, Sov.J.N.Phys 37(1983)]
Infinite fermi- liquid(two-body dissipation)
empirical factor from fitting exp. data
Generalized Fermi liquid (GFL) model
(extended to GDR energies of gamma- rays)
[S. Mughabghab, C. Dunford PL B487(2000); Ext.:V.A. Plujko, O.O.Kavatsyuk, Proc. 11th Int. Symp. Capture Gamma-Ray Spectr. and Related Topics (CGS 11), 2002, 793.]
-” fragmentation” component
RSF for gamma-decay
[V.A.Plujko, NPA649 (1999); Acta Phys. Pol. B31 (2000) 435.
V.A. Plujko, S.N. Ezhov, M.O. Kavatsyuk et al,J.Nucl.Sci Techn. (2000);
Plujko V. A., Kadenko I. M., Kulich E. V., Goriely S. et al
Proc. of Workshop on photon strength functions and related topics, Prague,
June 17-20, 2007, PSF07, 2008; http://arxiv.org/abs/0802.2183]
Approximation of strong collective state for response function
Doorway state approach for collisional relaxation time
At U=0, width is similar to that proposed by S.Coriely ( PhL. B436(1998) 10)
RSF for photoabsorption
Axially deformed nuclei - n=2;
Spherical nuclei Deformed nuclei
Berman B.L., Fultz S.C. // Rev. Mod. Phys. – 1975. – Vol. 47. – P. 713 – 761.