The nucleon momentum and density distribution of the 4He nucleus using the Morse potential

The nucleon momentum and density distribution of the 4He nucleus are calculated by using the Morse single-particle potential. The parameters for the momentum distribution n(fc) are determined by fitting either the charge form factor to the available experimental data of the elastic electron scattering by 4He or the momentum distribution to the corresponding "experimental" values. The calculations can be performed partly analytically and the results show a considerable overall improvement with respect to those obtained with the oscillator shell model. The r.m.s radius of the charge density distribution determined by fitting the charge form factor is in very good agreement with the vaiues obtained by means of model independent analysis.

The dependence of the nuclear charge form factor on short range correlations and surface fluctuation effects

An investigation is carried out in order to study effects, originating from fluctuations of the nuclear surface, to the elastic charge form factor of light nuclei in which the two-body part of the short range correlation factor is also included through a Jastrow-type correlation function. It is found that if these effects are taken into account in the uncorrected (harmonic oscillator) part of such a form-factor for the 4He, l6O and 40Ca nuclei, the quality of the fitting is improved. In addition, they lead to a drastic change in the asymptotic behaviour of the point-proton form factor which now drops off for large values of the momentum transfer q quite slowly that is as const.•q^-4.

Correlated charge form factors and densities of the sd-shell nuclei

The expression of the two body term in the fac­ tor cluster expansion of the charge form factor of 40Ca is derived.lt contains the harmonic oscillator (HO) parameter bx and the parameter λ which originates from the Jastrow correlation function. This expression together with the corresponding one of 16O nucleus helps to find a mass de­pendence of λ and an approximate and fairly simple expres­ sion of the two body term of open shell nuclei in the region 16<A<40 which contains one free parameter, the HO parameter bi. The fitting to the corresponding experimen­tal charge form factor is quite improved in comparison to the HO one without correlations.

Systematic study of the effect of short range correlations on the form factors and densities of s-p-d shell nuclei

Analytical expressions of the one- and two-body terms in the cluster expansion of the charge form factors and densities of the s-p and s-d shell nuclei with N=Z are derived. They depend on the harmonic oscillator parameter 6 and the parameter β which originates from the Jastrow correlation function. These expressions are used for the systematic study of the effect of short range correlations on the form factors and densities and of the mass dependence of the parameters ò and β. These parameters have been determined by fit to the experimental charge form factors. The inclusion of the correlations reproduces the experimental charge form factors at the high momentum transfers (q > 2 fm^-1). It is found that while the parameter β is almost constant for the closed shell nuclei, 4He, 16O and 40Ca, its values are larger (less correlated systems) for the open shell nuclei, indicating a shell effect in the closed shell nuclei.