Coulomb potentials and the energy-angular momentum balance in heavy ion transfer reactions

Oertzen, W. von

doi:10.1007/bf01418132

Cited by 7 publications

(8 citation statements)

References 17 publications

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“…2c). This discrepancy is generally observed in heavy ion transfer with charge transfer [26]. As discussed in [26] the dominant reason for this is the large change in the Coulomb interaction if charge is transfered from a light to a heavy nucleus (or vice versa).…”

Section: Ls Interaction Is Includedmentioning

confidence: 90%

“…This discrepancy is generally observed in heavy ion transfer with charge transfer [26]. As discussed in [26] the dominant reason for this is the large change in the Coulomb interaction if charge is transfered from a light to a heavy nucleus (or vice versa). This reflects itself in the distorted waves of the final channel, for which, however, generally the asymptotic charge procuct is used, in our case (Z e +1)(Zr-1)=5 x 55.…”

Section: Ls Interaction Is Includedmentioning

confidence: 90%

“…This reflects itself in the distorted waves of the final channel, for which, however, generally the asymptotic charge procuct is used, in our case (Z e +1)(Zr-1)=5 x 55. The main deficiency can thus be removed by introducing an additional potential in the interaction region [26] which takes into account the gradual change to the asymptotic charge product. This additional potential A V c (see Table l) has Woods-Saxon shape and is calculated in such a way that it removes the effect of charge transfer on the total potential (nuclear+ coulomb) at distances corresponding to the Coulomb barrier.…”

Section: Ls Interaction Is Includedmentioning

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: Ls Interaction Is Includedmentioning

confidence: 90%

Section: Ls Interaction Is Includedmentioning

confidence: 90%

Section: Ls Interaction Is Includedmentioning

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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“…With the po- Table 1, and Qo = -7.8 MeV tential parameters of [11] a reasonable overall agreement is achieved between FRDWBA calculations and the data. However, as observed in all charged particle transfer reactions, the position of the grazing maximum is not correctly reproduced [19]. The effect is most likely due to the strong perturbation introduced by the change of the Coulomb interaction.…”

Section: Angular Distributions and Reaction Asymmetries For (Lzcmentioning

confidence: 92%

Study of reaction asymmetries and spin orbit interaction of13C and11B in (12C,13C) and (12C,11B) reactions on208Pb

et al. 1984

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Angular distributions of neutron pick-up and proton stripping reactions in the interaction of ~=C on =~ have been studied at EL= 101 MeV with high accuracy using a Q3D magnetic spectrometer. Angular distributions of the single particle states are discussed in terms of reaction asymmetries Aij(O ). With these quantities the relative changes of the shapes of angular distributions can be studied in detail. The transfered lvalue has been found to have a large effect on the shapes. For the case of 13C an overall description of this quantity is obtained, if a spin-orbit interaction for ~3C is introduced with a sign which is opposite to that found in (~4C, 13C) reactions. For the case of ~B the reaction asymmetries cannot be described by a spin-orbit interaction. The possible origin of the spin-orbit effects is discussed. The particular discrepancies to a simple DWBA description (without spin-orbit interaction) found in both the ~aC and 11B angular distributions must be attributed to coupling effects in the initial channel, where the 2 + state of 1~C and 3-state of 2~ are excited, and to smaller extend to higher order couplings in the final channel.

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“…The sensitivity of the DWBA calculations on the cancellation V~-Vv~O depends on the optical model parameters used. The weaker the real (and the imaginary) part of the optical model potential the stronger< is the effect of the cancellation ~-VF=0 [19]. In these cases the difference A V can be a large fraction of the scattering potentials.…”

Section: B) Angular Distributionsmentioning

confidence: 97%

Two proton transfer reactions between pairing rotational states with 104 MeV16O on142Nd,144Sm,148Sm and152Sm

et al. 1976

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(160, 14C) reactions on target nuclei with open proton shells, which are members of protonpairing rotational bands have been studied. For all target nuclei strong transitions to the ground states are observed. The reduced groundstate transition strength's (after removal of Q-value dependence) are almost equal for all four target nuclei. Additional data on (160, 15N), (160, 13C) and (160~ 12C) reactions are used to discuss the enhancement in the two proton transfer.

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Coulomb potentials and the energy-angular momentum balance in heavy ion transfer reactions

Abstract: Coulomb terms in optical model parameters and in the effective interaction are discussed for DWBA in charged particle transfer in heavy ion reactions. It is shown that certain discrepancies in shapes of calculated angular distributions are due to incorrect treatment of Coulomb terms.

Cited by 7 publications

References 17 publications

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

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

Study of reaction asymmetries and spin orbit interaction of13C and11B in (12C,13C) and (12C,11B) reactions on208Pb

Two proton transfer reactions between pairing rotational states with 104 MeV16O on142Nd,144Sm,148Sm and152Sm

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