Microscopic ion-ion spin-orbit potential

Moffa, P.J.

doi:10.1103/physrevc.16.1431

Cited by 18 publications

(7 citation statements)

References 23 publications

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“…The spin dependence of the heavy ion interaction is only negligibly due to the spin dependence of the nucleon-nucleon or nucleon-nucleus interaction, because folding models based on these underestimate the experimental result by two orders of magnitude [11,12]. Recent work [14][15][16] suggests that the spin dependence observed is rather an effective potential due to the coupling of different nucleon-exchange and inelastic channels.…”

Section: Discussionmentioning

confidence: 95%

“…The first studies of the spin dependent interactions of heavy ions [7][8][9][10] have shown that strong effects are observed, which, if attributed to an L.S interaction, cannot be traced back to the spin dependence of the nucleon-nucleon interaction. Models for the L.S interaction of heavy ions [11][12][13], where the nucleon-nucleon interaction is folded with the nuclear densities, tend to give L.S potentials whose strength is generally a factor 10-100 too small. It was realised recently that different channel couplings due to transfer reactions and inelastic excitations can contribute in second order to the polarisation and effectively be responsible for the spin dependent interactions [14][15][16].…”

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confidence: 99%

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Study of spin-orbit interaction of13C and15N nuclei in14C induced transfer reactions on138Ba

et al. 1983

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Angular distributions of single nucleon transfer reactions populating single particle states in the reactions 138Ba(14C, 15N)137Cs and 138Ba(14C, 13C)139Ba have been studied. The shapes of the angular distributions show differences for different final configurations. Using the reaction asymmetry it is possible to describe these differences consistently for all transitions by a spin-orbit potential. The polarisation of the outgoing fragments is discussed and its dependence on final configurations is explained. The spin-orbit potentials deduced from the reaction asymmetry are large, as compared to predictions of folding potentials. They are, however, consistent with measurements of spin-flip probabilities. The origin of the L-S interaction is to be found in coupling effects of second order in the heavy ion reaction. I. MotivationRecent studies of direct reactions with heavy ions have shown that there are various observable effects connected with the spins of the interacting nuclei [1][2][3]. The most obvious effects, known from work with light particles, are related to the polarisation of reaction products produced in reactions and to analysing powers in reactions induced by polarised projectiles [4]. Polarisation and non-vanishing analysing powers can be produced by the vector coupling of angular momenta and spins in a surface reaction where only particular coupling schemes are strongly favoured. The clearest case for this circumstance can be found in the polarisation of final spins in Coulomb excitation [5]. This dynamic polarisation can be produced in any direct reaction in a one step interaction. The notion of an interaction potential containing the scalar product of orbital angular momentum and spin, L-S, is the second alternative. The L.S interaction can be due to the primary spin dependence of the nucleon-nucleon interaction [6]. The interplay of the dynamical polarisation with this L.S interaction produces a great variety of phenomena arising from the spin degrees of freedom in nuclear reactions (see for example [4]). The first studies of the spin dependent interactions of heavy ions [7][8][9][10] have shown that strong effects are observed, which, if attributed to an L.S interaction, cannot be traced back to the spin dependence of the nucleon-nucleon interaction. Models for the L.S interaction of heavy ions [11][12][13], where the nucleon-nucleon interaction is folded with the nuclear densities, tend to give L.S potentials whose strength is generally a factor 10-100 too small. It was realised recently that different channel couplings due to transfer reactions and inelastic excitations can contribute in second order to the polarisation and effectively be responsible for the spin dependent interactions [14][15][16]. The case with heavy ions is rather interesting because it offers possibilities to study different origins of the spin dependent interactions. The present work presents data on reaction asymmetries (introduced in [2,9]) for 15N

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Section: Discussionmentioning

confidence: 95%

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confidence: 99%

Study of spin-orbit interaction of13C and15N nuclei in14C induced transfer reactions on138Ba

et al. 1983

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“…We choose the same parameters for the radial dependence as the main potential for the scattering of 15N as given in Table 1. Several authors [20][21][22] have calculated the strength of spin-orbit potentials for heavy ions. Generally a dependence of V~o with a proportionality to 1/A or I/A 2/3 is predicted.…”

Section: Polarisation and Reaction Asymmetry A) Polarisationmentioning

confidence: 99%

Spin alignment and polarisation in the (16O,15N) transfer reactions

et al. 1979

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The spin alignment of the 15N3/2, (6.33MeV) state was measured in the S SSr(160, 15N)89y reaction at EL=96MeV using the 7-recoil method. Angular distributions of excited states in ~SN and Sgy were measured with high accuracy. The analysis in terms of DWBA shows that the spin alignment is correctly described by the usual reaction models. The polarisation of the outgoing 15N1/2(GS ) and 15N*/2(6.33MeV ) is discussed. It is shown that cross section differences for transitions to final states with different configurations are sensitive to a spin-orbit potential of ~SN. The strength and sign of the spin-orbit potential for 15N is determined.

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“…Hence, folding techniques may well be applied to evaluate this part of the interaction (a procedure which is admittedly rather involved when going over to the interaction of heavy ions with each other, however, a more detailed discussion of this problem is to appear elsewhere [20]). Calculations of the spinorbit term were presented by Moffa [15] while [16] contains the evaluation and discussion of the ocntributions to the imaginary part of the potential as originating from the rotational states. However, at present we recommend to evaluate V~o and the Coulomb potential by aid of folding techniques and to use for the time being phenomenological substitutes for the remaining terms.…”

Section: Nucleon-nucleus Scatteringmentioning

confidence: 99%