Improvedd+4He potentials by inversion: The tensor force and validity of the double folding model

Abstract

Improved potential solutions are presented for the inverse scattering problem for d+ 4 He data. The input for the inversions includes both the data of recent phase shift analyses and phase shifts from RGM coupled-channel calculations based on the NN Minnesota force. The combined calculations provide a more reliable estimate of the odd-even splitting of the potentials than previously found, suggesting a rather moderate role for this splitting in deuteron-nucleus scattering generally. The approximate parity-independence of the deuteron optical potentials is shown to arise from the nontrivial interference between antisymmetrization and channel coupling to the deuteron breakup channels. A further comparison of the empirical potentials established here and the double folding potential derived from the M3Y effective NN force (with the appropriate normalisation factor) reveals strong similarities. This result supports the application of the double folding model, combined with a small Majorana component, to the description even of such a loosely bound projectile as the deuteron. In turn, support is given for the application of iterativeperturbative inversion in combination with the double folding model to study fine details of the nucleus-nucleus potential. A d-4 He tensor potential is also derived to reproduce correctly the negative 6 Li quadrupole moment and the D-state asymptotic constant. 25.45.De,24.10.-i,21.60.Gx,24.75.+i Typeset using REVT E X 1 Contents of the paper. 1. Introduction 2. The role of parity dependence in IP inversion 3. Stabilised inversion of the d-4 He empirical data for 0 < E d ≤15 MeV 4. Inversion of RGM S(l) with breakup channel contributions 5. Validity of double folding model for d-4 He interaction and similar systems. 6. Tensor d-4 He potential and the 6 Li-quadrupole moment. Conclusions I. INTRODUCTIONMany basic features of the interactions between light composite particle are now well established. In particular, a good description [1]-[6], of the interactions of light nuclei such as d + t, t+ 3 He, 4 He+ 4 He etc. is obtained from a deep attractive potential with Pauliforbidden states with the addition of parity dependence, Young scheme splitting and a spinorbit interaction. Importantly, this type of interaction is now justified from microscopic considerations, both in quasi-classic picture [4] and also in quantum mechanical shell-model framework [1,7]. These results lead to a general comprehensive understanding of the relations between various interaction models which appear, at a first glance, to contradict to each other.Nevertheless, a number of finer features of the interaction, notably the role of the dynamic polarisation of loosely bound projectiles such as d or 6,7 Li when combined with antisymmetrization effects, are not yet fully understood despite many previous efforts. The existing problems and contradictions are illustrated by the following example. On the one hand, it is well known (see e.g. [1], [8]- [13]) that antisymmetrization and coupled-channel effects in composite parti...

Radiative p 16O Capture at Astrophyiscal Energies

“…Continuing study the total cross sections of the radiative proton capture on 16 O, let us firstly consider classification of orbital states for the p 16 О system according to Young tableaux. The orbital Young tableau {4444} [14] corresponds to the ground bound state of 16 O, therefore we have {1}  {4444}  {5444} + {44441} [23] for the p 16 О system.…”

“…This approach was used by us still in works [12,13], where FSs follow from the classification of cluster states according to Young tableaux [14]. Furthermore, in [15,16] in the MPCM with tensor forces the possibility of the correct reproduction practically of all characteristics of 6 Li was demonstrated, including its quadrupole moment. Subsequently, in [17][18][19][20] on the basis of the MPCM we have presented the possibility of description of the astrophysical S-factors or the total cross sections of almost 30 He, 4 He 12 C systems at thermal and astrophysical energies (see also [3][4][5][6][7][8]).…”

“…This phase involves hydrogen and a helium shell that burn alternately surrounding an inactive stellar core. The 16 O(p,) 17 16 O abundance ratio in small grains which are formed by the condensation of the material ejected from the surface of AGB stars via strong stellar winds [22].…”

“…Continuing study of thermonuclear reactions in the frame of the modified potential cluster model with forbidden states [17][18][19][20] let us consider the 16 O(p,) 17 F process, which takes part of the CNO cycle [17,18] and has additional interest, since it is the reaction at the last nucleus of 1p-shell with the forming of 17 F that get out its limit. As we assume in [17][18][19][20], the bound state (BS) of 17 F is caused by the cluster channel of the initial particles, which take part in the reaction.…”

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Abstract :The possibility of description of the experimental data for the astrophysical S-factor of the proton radiative capture on 16 O to the ground and first excited states of 17 F was considered in the frame of the modified potential cluster model with forbidden states and classification of the states according to Young tableaux. It was shown that on the basis of the E1 transitions from the P states of p 16 O scattering to the bound states of 17 F in the p 16 O channel, it generally succeed to explain the value of measured astrophysical S-factors and reaction rates at astrophysical energies.

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