ATOMKI Közlemények 20. (1978)

1. szám - Tudományos közlemények - Angeli I.-M. Csatlós: Héj-effektusok atommagok elektromos töltés-sugarában

1. Introduction Several methods are used in the determination of nuclear sizes. According to the measurements performed by different methods, the nuclear radius is approximately proportional to the one third power of the mass number A. The different values of the proportionality factor are, however, characteristic of the experimental methods rather than of the nuclei investigated. Therefore, in order to look for deviations ("fine structure") from the simple A1'3-rule, the term nuclear radius should be defined in accordance with the respective measuring method. Electromagnetic methods (fast electron scattering, muonic X-rays, optical and Ka isotope shifts) determine moments or differences in moments of the charge distribution in nuclei with a fairly good accuracy. For practical reasons the results of these experiments are often presented in terms of the second moment; this root-mean-square (rms) charge radius <r2>^2 characterizes the electric charge distribution in nuclei, and consequently the proton distribution. In ref. [1] it has been shown that - for the isotopic sequence of an element - the deviation of rms charge radii from the rough A1/3 dependence follows simple trends determined by neutron shell structure and nuclear deformation. In this paper the fine structure in rms radii through isotonic, isobaric and iso-symmetric (N-Z=const.) sequences will be investigated by using experimental data from the literature. The sources and treatment of experimental results together with a table of rms charge radii, are described in the appendix. the normalized rms radii In order to look for fine structure, 2 <r 2 > exp 2 Ч2 <r > calc • • ■ ? l/г will be investigated, where <r > charge radius, and exp <1?2>calc = ''/f n0 (A)A1/3 (2) r0(A) being a slowly varying function of the mass number, e.g. r0 (A) = 1.15 + 1.80 A~ 2^3 -1.20 A-^3 (3) The constants in eq.(3) are the rounded values of those given on p.5 of ref. [2]. 2. Isotonic sequences Normalized rms radii p for isotonic sequences are plotted vs. proton number Z in figs, l.a, b. Sequences consisting of more (1) is the experimental rms

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