E. M. Tursunov

Three-body continuum states on a Lagrange mesh

Abstract Three-body continuum states are investigated with the hyperspherical method on a Lagrange mesh. The R -matrix theory is used to treat the asymptotic behaviour of scattering wave functions. The formalism is developed for neutral as well as for charged systems. We point out some specificities of continuum states in the hyperspherical method. The collision matrix can be determined with a good accuracy by using propagation techniques. The method is applied to the 6 He ( = α + n + n ) and 6 Be ( = α + p + p ) systems, as well as to 14 Be ( = Be 12 + n + n ). For 6 He, we essentially recover results of the literature. Application to 14 Be suggests the existence of an excited 2 + state below threshold. The calculated B (E2) value should make this state observable with Coulomb excitation experiments.

Comparative variational studies of 0+ states in three-α models

Abstract Three variational approaches, the hyperspherical-harmonics, Gaussian-basis and Lagrange-mesh methods involving different coordinate systems, are compared in studies of 0+ bound-state energies in 3α models. Calculations are performed with different versions of the shallow Ali–Bodmer potential (with and without Coulomb) and with the deep Buck–Friedrich–Wheatley potential. All three methods yield very accurate energies. Their advantages and drawbacks are evaluated. The implications of the disagreement between the obtained results and the experimental 12C energies in 3α models with Coulomb interaction are discussed.

β delayed emission of a proton by a one-neutron halo nucleus

Abstract Some one-neutron halo nuclei can emit a proton in a β decay of the halo neutron. The branching ratio towards this rare decay mode is calculated within a two-body potential model of the initial core + neutron bound state and final core + proton scattering states. The decay probability per second is evaluated for the 11 Be, 19 C and 31 Ne one-neutron halo nuclei. It is very sensitive to the neutron separation energy.

Analysis of the 6He β-decay into the α+d continuum within a three-body model

The beta-decay process of the

Unique decay process: {beta}-delayed emission of a proton and a neutron by the {sup 11}Li halo nucleus

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Theoretical analysis of the astrophysical S-factor for the capture reaction α + d → 6Li + γ in the two-body model

He halo nucleus into the alpha+d continuum is studied in a three-body model. The

Gamma-delayed deuteron emission of the Li6(0+;T=1) halo state

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Updated three-body model of 6He β decay into the α+d continuum

He nucleus is described as an alpha+n+n system in hyperspherical coordinates on a Lagrange mesh. The convergence of the Gamow-Teller matrix element requires the knowledge of wave functions up to about 30 fm and of hypermomentum components up to K=24. The shape and absolute values of the transition probability per time and energy units of a recent experiment can be reproduced very well with an appropriate alpha+d potential. A total transition probability of 1.6E-6 s

THEORETICAL STUDY OF THE 11Li β DECAY INTO THE DEUTERON CHANNEL IN A CLUSTER MODEL

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Analysis of theHe6β decay into theα+dcontinuum within a three-body model

is obtained in agreement with that experiment. Halo effects are shown to be very important because of a strong cancellation between the internal and halo components of the matrix element, as observed in previous studies. The forbidden bound state in the alpha+d potential is found essential to reproduce the order of magnitude of the data. Comments are made on R-matrix fits.