Two-nucleon Stripping Reactions Research Articles

Correlated two-nucleon stripping reactions

The cross sections for the stripping of two correlated nucleons from light and medium-mass nuclei are considered. Such reactions are of interest both as a means for populating and identifying low-lying excited states of very exotic nuclear species and as a potential direct spectroscopic probe of two-nucleon correlations in such systems. A calculation scheme that combines the full shell model two-nucleon spectroscopic amplitudes with eikonal reaction theory is presented. The theoretical predictions of the method, and of more approximate schemes, are compared with new data on two-proton removal from $^{28}\mathrm{Mg}$. The combined full shell model structure amplitudes and reaction dynamics predictions are in good agreement with the available measurements. First indications of the sensitivity of the reaction mechanism to the spatial and angular momentum structure of the stripped two-nucleon wave functions are also discussed and clarified.

Two-nucleon transfer: Random-phase approximation theory, pairing vibrations, and the extended basis shell model

Previous calculations have shown that the accurate prediction of two-nucleon overlap factors requires the inclusion of very large numbers of highly excited configurations. These "extended basis shell model" calculations treat a pair of nucleons added to an inert core. In the present paper, the two-particle random-phase approximation theory of Vary and Ginocchio is used to generalize the extended basis shell model to include the effect of core correlations. Including them is shown to have a small effect on two-nucleon stripping reactions, such as $^{16}\mathrm{O}(t, p)^{18}\mathrm{O}$. However, the random-phase approximation enables us to include the effect of the highly excited single-particle states on the transition amplitudes for the pickup of a pair, e.g., $^{16}\mathrm{O}(p, t)^{14}\mathrm{O}$. Because the admixed states have wave functions which are large in the surface and exterior regions, they result in large enhancements of pickup cross sections. We have also studied the breakdown of the random-phase approximation, when eigenvalues become complex. We provide a proof, for an arbitrary two-body interaction, that the potential strength for which the random-phase approximation eigenvalues become complex, is the minimum strength for which nontrivial solutions to the Hartree-Fock-Bogolyubov equations exist.NUCLEAR REACTIONS Core correlations included in EBSM calculations of two nucleon stripping reactions using particle-RPA; influence of EBSM on two nucleon pickup reactions; breakdown of RPA.

Two-nucleon stripping reactions with tabakin potential

The theory of two-nucleon stripping reactions has been considered. Due to the short-range correlations in nuclei and to the strong repulsive nature of nuclear forces at very short distances, the short-range correlations in nuclei are investigated. To take into account the short-range correlations, the nucleon-nucleon interaction is taken as a short-range repulsive core surrounded by a long-range attractive potential. A more realistic potential is suggested by Tabakin as a separable but nonlocal interaction. The differential cross-sections for the two-nucleon stripping reaction (t, p) have been calculated in two different cases by taking Yamaguchi or Breitet al. type parameters for the Tabakin potential used. DWBA calculations have been used to calculate the angular distributions for different (t, p) stripping reactions on the different target nuclei31P,96Zr,116Sn,118Sn and206Pb. Good agreement is obtained between the present theoretical calculations and the experimental data. By fitting the calculated angular distributions to the experimental data, more reliable spectroscopic factors are extracted.

Coulomb (3He, n) stripping reactions

The theory of two-nucleon stripping reactions (3He, n) at projectile energies below the Coulomb barrier has been considered. By taking Coulomb distorted-wave functions for the interacting particles in the initial channel, a closed analytical form for the differential cross-section has been obtained. The present theoretical calculations are applied to the reactions9Be(3He, n)11C and11B(3He, n)13N. Moreover, calculations in the other two cases using the plane-wave Born approximation and the distorted-wave Born approximation are introduced. The agreement between the present theoretical calculations and the experimental data is satisfactory. Moreover, the spectroscopic factors are extracted by fitting the theoretical calculations with the experimental data.

Two-nucleon stripping reactions populating isobaric multiplets in the region 40 ≦ A ≦ 56

A DWBA analysis accounts for the experimental results concerning the ratio between transitions populating isobaric multiplets in the region 40 ≦ A ≦ 56, by using distorted waves of definite isospin.

Two-nucleon stripping reactions induced by 16O in 54Fe and 58Ni at 80 MeV

Both the ( 16O, 14N) and ( 16O, 14C) reactions have been investigated on 54Fe and 58Ni target nuclei at 80 MeV incident energy. Both reactions are selective. The kinematical conditions have been found to act in two ways: (i) the high-spin states are enhanced and (ii) the states involving nucleons in the f- or p-shells are favoured. Three groups of T = 1 analog states have been located in 56Ni and 60Zn from a comparison of the two transfer reactions on the same target, and configuration assignments are attempted.

Repulsive core effects in (t, p) stripping reactions

The two-nucleon stripping reactions seems to be a powerful tool in nuclear spectroscopy. I t is worth-while to treat it as exactly as possible. I t is worth-while to treat it as exactly as possible. I t is to consider the effect of the repulsive core in the two-nucleon interaction on the double-stripping reactions. We restrict ourselves to the (t, p) case. The most important feature of the (t, p) reactions lies in the following nine-fold nonseparable integral (1):

Finite range Coulomb stripping in (t, p) and (He3, n) reactions

The theory of two-nucleon stripping reactions in considered, taking into account the Coulomb distortion and the finite-range effects at projectile energies below the Coulomb barrier. Applying the results to the reactions N14(t, p)N16 and Be9(He3, n)C11 reliable agreement is observed with the experimental data especially in the forward direction.

Two-nucleon stripping processes

The theory of two-nucleon stripping reactions is developed in the distorted wave Born approximation. The two-nucleon forces responsible for the reaction are taken to be spin and isospin dependent and of finite range. Expressions for the angular distribution and polarization of the emitted particles are given. The angular correlation and circular polarization of γ-rays following the reaction are considered.

Two-nucleon stripping reactions on deformed nuclei

The (He 3, p) stripping process on spheroidal nuclei is carried out. Nilsson's wave functions are employed to represent the two captured nucleons. General properties of the cross-sections and selection rules are discussed.

Note on the two-nucleon stripping reaction

The magnitude of the two-nucleon stripping reactions is calculated using the pairing interaction model. The calculation also is applied to final states of collective type. For some types of reaction a collective enhancement of the reaction cross section is predicted.