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1.
The possibility of describing the astrophysical S factors for radiative 3He4He capture at energies of up to 15 keV and radiative 3H4He and 2H4He capture at energies of up 5 keV is considered on the basis of the potential cluster model involving forbidden states.  相似文献   

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A method is described to determine the potential difference, V g-V u, that will accurately reproduce the exchange and nuclear symmetry oscillations observed by Aberth et al. in their experimental work on He+-He differential scattering. It is demonstrated that at higher energies and angles the experimental results for 4He+-4He, 4He+-3He and 3He+-3He appear incompatible with one another when investigated in terms of a two-state scattering theory. This is an indication that at these energies and angles the theory may require modification to include the effects of coupling to higher states.  相似文献   

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A microscopic formalism for describing observed cross sections for deuteron breakup by threenucleon nuclei was developed on the basis of the diffraction nuclear model. A general formula that describes the amplitude for the reaction 2H(3He, 3Hep)n and which involves only one adjustable parameter was obtained by using expansions of the integrands involved in terms of a Gaussian basis. This formula was used to analyze experimental data on the exclusive cross sections for deuteron breakup by 3He nuclei at the projectile energy of 89.4MeV. The importance of employing, in calculations, a deuteron wave function that has a correct asymptotic behavior at large nucleon–nucleon distances was demonstrated.  相似文献   

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Final state interaction effects inpp→ pΛK + andpd3Heη reactions are explored near threshold to study the sensitivity of the cross-sections to thepΛ potential and theηN scattering matrix. The final state scattering wave functions between Λ andp andη and3He are described rigorously. The Λ production is described by the exchange of one pion and aK-meson between two protons in the incident channel. Theη production is described by a two-step model, where in the first step a pion is produced. This pion then produces anη by interacting with another nucleon  相似文献   

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Irregularities in the cross section of electron scattering off hydrogen and hydrogen-like He+, Li++, and Be+++ ions are studied using an s-wave model. The resonance structure and irregularities in the scattering data are compared. A unified approach based on an exterior complex scaling method is used in performing calculations. The potential splitting approach is used for calculations of scattering in systems with asymptotic Coulomb interactions.  相似文献   

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Forward dispersion relations for nucleon-4He scattering have been analyzed for 0 < Elab < 600 MeV with the help of new experimental data. Improving over a previous analysis restricted to E < 50 MeV the 4He3He n coupling constant is determined unambiguously as r = 3.2 ± 0.4 in agreement with information from stripping reactions. Moreover the strength of uncorrelated three nucleon exchange and the summed strength of mesonic exchange is determined.  相似文献   

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N/D equations taking into account the Coulomb interaction effects are used to consider the phase analysis data on 3He4He scattering and determine the nuclear vertex constants for the 7Be ? 3He4He vertex, where the beryllium nucleus is in the ground (3/2?) or first excited (1/2?) states. Information about the asymptotic normalization coefficients of the wave functions of the 7Be nucleus in the noted states is derived. The data obtained are used to calculate the astrophysical S factor for the 4He(3He, γ)7Be reaction.  相似文献   

12.
As a first application of the refined cluster model reaction theory we calculated the scattering states of He5 using a specific ansatz for the nucleon-nucleon forces. He4-n and H3-d channels are considered only. Our results agree qualitatively with the experimental values if available; in particular we were able to explain the narrow resonance in theD 3/2 He4-n channel as a consequence of the strong coupling to theS 3/2 T-d channel.  相似文献   

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A selection of new data obtained by the HERMES experiment at DESY is presented, which provides new insight into the QCD structure of the nucleon. Using polarized lepton beams and polarized targets, the spin-dependent structure function g 1(x) has been determined for 1 H, 2 H and 3 He. By also observing one of the produced hadrons it has been possible to extract the polarization distribution of individual quark flavours in the nucleon as well. Further information on nucleon structure has been obtained by observing (almost) exclusive reactions, which can be interpreted in terms of the recently introduced generalized parton distributions (GPDs). As an example of such data measurements of both the beam-spin and beam-charge asymmetries resulting from deeply virtual Compton scattering (DVCS) are presented. By embedding the deep-inelastic scattering process in the nuclear environment additional information can be obtained on nucleon structure and some QCD effects. The potential of this technique is illustrated by showing new results on tagged structure functions and hadronization in nuclei.Received: 30 September 2002, Published online: 22 October 2003PACS: 13.60.Hb Total and inclusive cross-sections (including deep-inelastic processes) - 13.88. + e Polarization in interactions and scattering - 14.20.Dh Protons and neutrons - 24.85. + p Quarks, gluons, and QCD in nuclei and nuclear processesG. van der Steenhoven: For the HERMES Collaboration  相似文献   

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The vector analyzing power has been measured for the elastic scattering of neutron-rich 6He from polarized protons at 71 MeV/nucleon. Two approaches based on local one-body potentials were applied to investigate the spin-orbit interaction between a proton and a 6He nucleus. An optical model analysis revealed that the spin-orbit potential for 6He is characterized by a shallow and long-ranged shape compared with the global systematics of stable nuclei. A semi-microscopic analysis with a α + n + n cluster folding model suggests that the inclusion of realistic interaction between a proton and the α core is important in describing the p-6He elastic scattering.  相似文献   

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The possibility of describing new experimental data on the astrophysical S factor of radiative 4He12C-capture at energies ranging from0.9 to 4 MeV in the context of the potential cluster model is considered.  相似文献   

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Calculations of microscopic optical potentials (OPs) (their real and imaginary parts) are performed to analyze the 6 He + p elastic-scattering data at a few tens of MeV/nucleon (MeV/N). The OPs and the cross-sections are calculated using three model densities of 6He . Effects of the regularization of the NN forces and their dependence on nuclear density are investigated. Also, the role of the spin-orbit terms and of the non-linearity in the calculations of the OPs, as well as effects of their renormalization are studied. The sensitivity of the cross-sections to the nuclear densities was tested and one of them that gives a better agreement with the data was chosen.  相似文献   

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Since the early 1970s, experiments have been performed to investigate the fragmentation of the lightest nuclei (d, 3H, 3He, and 4He) on protons at intermediate energies (~0.2–2 GeV per nucleon). These experiments were set up in ITEP and LHE JINR and realized in an exclusive approach with the help of liquid hydrogen bubble chambers. This investigation is of great interest from two points of view: first, the possibility of detailed theoretical analysis of the data obtained in 4π geometry on the basis of a good understanding of the structure of the wavefunctions of these nuclei and, second, the search for exotic interaction mechanisms. This overview presents the latest, most interesting results of the ITEP experiment on the study of 4Hep interactions at 4He momenta of 2.7 and 5 GeV/c, on cross sections, elastic scattering, pair correlations of secondary nucleons, cumulative production of nucleons and the lightest nuclei (d, 3H, and 3He), the main features of exclusive reactions, and the search for possible multiquark bag production (dibaryons and tribaryons). The essential results of the independent JINR experiment at 8.6 and 13.6 GeV/c also come under discussion.  相似文献   

20.
A partial-wave analysis of elastic 4He4He scattering is performed in the energy range 40–50 MeV.  相似文献   

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